Migration Assistant Stuck? How to Move to a New Mac Fast

Safety correction, 18 October 2026: Added safeguards before cleanup and erasure, corrected personal-folder selection and FileVault guidance, and clarified that stalled counters do not prove failure. Temporary protection changes must be reversed after migration. The corrections use the Apple guidance linked below; no new device testing was performed.

Migration Assistant is the single step where setting up a new Mac goes wrong, and it goes wrong in a specific, repeatable way. The box is open, the new machine is on the desk, and the progress bar has been sitting at 45 percent for two hours telling you there are 26 hours remaining. Ten minutes later it says four hours. Ten minutes after that it says 26 hours again. Nobody in the room knows whether the right move is to wait, to restart, or to give up and copy files by hand.

The reason this happens is not that Migration Assistant is broken. It is that Migration Assistant picks its own transport, it prefers a wireless path that most people never realise is being used, and the default situation in almost every home — two Macs sitting next to each other, both joined to the same Wi-Fi network — is close to the worst configuration the tool supports. Apple documents the transport selection behaviour, but it does so in the Apple Platform Deployment guide aimed at IT administrators, not in the consumer support article that a person setting up a laptop is going to read.

This article settles three things. First, which transfer method you should actually use, ranked, with the mechanism behind why the ranking looks the way it does. Second, how to interpret an estimate that says one minute remaining for an hour without treating it as proof of either success or failure. Third, the Apple silicon details that most guides still get wrong, including the very common instruction to hold T at startup, which has not applied to any Mac Apple has sold as new since 2023.

The timing matters right now. Apple extended its 2026 Back to School promotion in the US to 24 September 2026, according to reporting from MacRumors and 9to5Mac on 11 August 2026, and macOS 27 Golden Gate is expected in September 2026 as the first Apple silicon only release. A lot of people are about to migrate to a new Mac in the next six weeks.

Key Takeaways

• Migration Assistant picks the transport, not you — Apple's deployment documentation states that unless Wi-Fi has been turned off on the source Mac, the two Macs establish a peer-to-peer Wi-Fi connection, which is why turning Wi-Fi off on the old Mac is the highest-value single change you can make.
• Target Disk Mode does not exist on Apple silicon — holding T does nothing on an M-series Mac; the equivalent is Share Disk, reached through macOS Recovery under Utilities, and it presents the volume as a network share rather than a local disk.
• The estimate is not a diagnosis — small-file and metadata work is one possible explanation for a slow final stage; Apple does not document the estimator algorithm.
• Check progress and both Macs — an unchanged estimate or byte counter alone does not establish failure. Apple warns that large transfers can take hours and appear to pause; check for errors, power and connection problems before deciding to retry.
• Migrating from a Time Machine backup is the most reliable fallback — it removes the second Mac, the network, and the interactive session from the equation entirely, and it is the workaround that resolved the Tahoe migration failure reported on Apple's own community forums.

What Migration Assistant Actually Is

Before ranking methods, it helps to be precise about what the tool does, because a lot of the anxiety around it comes from people assuming it does more than it does.

What Apple Says It Moves

Apple's support article Transfer to a new Mac with Migration Assistant, last published 10 February 2026, opens with a one-sentence scope statement: Migration Assistant transfers documents, apps, user accounts, and settings from one Mac to another, and it does not delete information from your old Mac or replace the operating system on your new Mac.

That second half is the important part, and it is why migrating is safer than its reputation suggests. Greg Gant made the same point in a January 2026 post arguing in favour of the tool: on modern macOS the system volume is read-only and cryptographically sealed, so the operating system you get on your new Mac stays exactly as Apple installed it. Migration Assistant cannot drag a corrupted old system across, because it never touches the system volume. What it drags across is your data volume.

In the macOS Tahoe 26 Mac User Guide, Apple breaks the selection screen into five categories:

Category	What it covers
Applications	Third-party apps in /Applications. Apple notes that incompatible apps, or apps with newer versions already installed, may not be transferred or may not be usable
User accounts	Each account and its home folder, with a disclosure arrow to pick individual folders such as Documents, Pictures, Movies, Desktop and Downloads
Other Files & Folders	Files outside the home folders, on the data volume
Privacy & Security Settings	Privacy permissions and related settings
System & Network	System and network settings, expandable to select individual items

Apple's Platform Deployment guide adds two details the consumer article omits: the user's ~/Library folder is always migrated, and migration includes hidden folders and files, giving SSH keys as the specific example, unless a management configuration excludes them. If you have wondered whether ~/.ssh comes across, that is the documented answer.

Howard Oakley of The Eclectic Light Company adds that Migration Assistant attempts to migrate the contents of well-known hidden folders including /usr/local, though it can struggle where those locations have been heavily customised. That one sentence explains most of the Homebrew grief covered later.

What It Does Not Touch

It does not reinstall or modify macOS. It does not erase the old Mac. It does not transfer the encrypted form of your data; as Glenn Fleishman explains in Macworld, the migration copies the decrypted contents, because the destination needs readable data to populate the new machine. And it does not, on its own, handle software licensing.

It is also not, in Gant's phrase, a janitorial service. It is a wholesale transfer tool. Every orphaned preference file, every abandoned application support folder, and every cache directory that has been quietly growing since 2019 comes with you unless you clean up first or deselect it.

Where It Lives on Your Mac

If the new Mac is still showing Setup Assistant — the flow that asks for your country and network — migration is built into that flow and you do not open anything separately.

If you have already completed setup, Migration Assistant is a standalone app. Apple documents two routes: the Utilities folder inside Applications, and System Settings → General → Transfer or Reset → Open Migration Assistant. Opening it quits all your other apps and logs you out, so save your work first.

The difference matters. Migrating during Setup Assistant lets Migration Assistant create the account cleanly. Migrating afterwards means an account already exists, which brings the same-short-name problem covered later.

Decide First: Migrate, Migrate Selectively, or Start Clean

The most common mistake is not picking the wrong transport. It is not asking this question at all, and reflexively dragging fifteen years of accumulated state onto a machine you bought specifically to be fast.

The Case for Migrating Everything

You get back to work in one session. Every application preference, every mail account, every browser profile, every keyboard shortcut and Finder sidebar arrangement survives. For anyone whose Mac is a work tool rather than a hobby, this is almost always correct, and Gant's conclusion — that for most users, most of the time, you should use Migration Assistant — is the right default advice.

Oakley adds a timing argument: if you intend to take across much of what is on the old Mac, including your current user settings, the best time to do that is when you are first configuring the new Mac. Migrating during Setup Assistant avoids the account-collision handling entirely.

The Case for a Clean Start

There are specific situations where migrating forward is the wrong call:

• The old Mac was misbehaving in ways you never diagnosed, particularly login-time slowness, permission dialogs that keep reappearing, or a mail app that has become unreliable. Those problems live in ~/Library, and ~/Library is always migrated.
• You are crossing the Intel to Apple silicon boundary and a meaningful share of your installed software is Intel-only. Migrating brings binaries that are on a countdown clock. See the section on Rosetta below.
• You have a heavily customised /usr/local from the Intel Homebrew era, plus a large developer toolchain. The migrated result is frequently a machine with two half-working Homebrew prefixes.
• Your old machine is genuinely close to full and most of that is stuff you have not opened in years.

The honest cost of a clean start is time, and more of it than people expect. You are re-authenticating every account, reinstalling every app, and rebuilding every preference. Oakley's warning applies: manual migration is much harder and risks omitting things you needed. Our complete Mac migration walkthrough covers the manual path in more detail if you decide to go that way.

A Decision Table

Your situation	Recommended approach
Same architecture, recent macOS on both, machine behaving normally	Migrate everything during Setup Assistant
Intel Mac to Apple silicon, mostly App Store and mainstream apps	Migrate user accounts and files, deselect Applications, reinstall apps natively
Intel Mac to Apple silicon, heavy developer toolchain	Migrate user accounts and files only; rebuild Homebrew and language runtimes from scratch
Old Mac has unexplained login or permission problems	Select the needed personal folders under each User account, or copy those folders manually from a verified backup and rebuild settings
Old Mac is dead or unbootable	Migrate from the most recent Time Machine backup
Work or school Mac under device management	Talk to IT first; a managed enrolment can change what is allowed
You want a clean machine but cannot afford the downtime	Migrate everything now, clean up later with a scheduled afternoon

Apple places Documents, Pictures and other personal folders under User accounts. Selecting only Other Files & Folders does not include those account folders. To avoid carrying unwanted settings, copy the needed personal folders manually rather than the whole home folder, then set up apps and preferences afresh. Selective migration alone does not diagnose or guarantee a fix for the old problem.

The Middle Path Most People Should Take

Deselect Applications, keep everything else. You keep your data, your accounts, your settings and your ~/Library, and you reinstall applications from their current installers so that every binary on the new machine is a current, correctly signed, architecture-appropriate build. It costs you an evening of downloads and it removes the largest single category of post-migration weirdness.

If you go the other way and migrate applications, plan a cleanup pass afterwards. Removing an app by dragging it to the Trash leaves its support files behind, which is exactly the sediment you were trying to avoid; our guide to removing an app and all of its leftover files covers how to do that properly.

The Transfer Methods, Ranked

This is the section that determines whether your migration takes ninety minutes or twenty-six hours.

How Migration Assistant Chooses a Transport

Apple documents this, but in the Apple Platform Deployment guide under Managed Migration Assistant for macOS, published 24 March 2026. The relevant passage states that Migration Assistant selects the best transport option for migration based off of speed, that the options include directly connecting over Wi-Fi, infrastructure Wi-Fi, Ethernet, and Thunderbolt, and that Migration Assistant also frequently checks to see if a faster option becomes available during migration.

Read that carefully, because there are three separate facts in it.

First, there are four transports, and two of them are wireless. Directly connecting over Wi-Fi is a peer-to-peer link between the two Macs. Infrastructure Wi-Fi is both Macs talking through your router. These are not the same thing and they perform very differently.

Second, the selection is automatic and speed-based. You do not choose. You can only change what is available for it to choose from.

Third — and this is the part almost nobody knows — the transport can change during the migration. Migration Assistant re-evaluates mid-transfer. This is the mechanical reason the time estimate swings wildly: the throughput it is extrapolating from is not stationary. A user on the MacRumors forums migrating to an M4 MacBook Pro in December 2024 reported watching exactly this, with the transfer starting on Ethernet and then switching to peer-to-peer partway through.

The same deployment page states the requirement plainly: unless Wi-Fi has been turned off on the source Mac, devices establish a peer-to-peer Wi-Fi connection. That sentence is the single most actionable fact in Apple's entire documentation of this tool.

Why Peer-to-Peer Wi-Fi Is the Worst Default

Here is the mechanism, and it is worth understanding rather than taking on faith.

A Mac's peer-to-peer Wi-Fi is Apple Wireless Direct Link, the same layer that carries AirDrop and AirPlay discovery. As the Yggdrasil Network project's technical write-up on AWDL explains, a device can be joined to an ordinary Wi-Fi access point and to an AWDL cluster at the same time using a single Wi-Fi radio, by rapidly switching between the radio channels of the two.

One radio. Two channels. The card cannot be on both at once, so it time-slices.

That produces a specific and unpleasant pair of consequences when you are migrating between two Macs that are both also joined to your home network:

• The peer-to-peer link only gets a fraction of the available airtime, because the radio keeps leaving to maintain the association with your router.
• Your home Wi-Fi degrades at the same time and for the same reason, which is why the rest of the household notices when someone starts a migration.

Layer on top of that the ordinary realities of a 2026 apartment: a crowded 5 GHz band, neighbouring networks, and two Macs sitting six inches apart, both transmitting loudly. The result is a link whose effective throughput varies minute to minute, which is precisely the input a time estimator handles worst.

Apple publishes no throughput figures for Migration Assistant on any transport. The only numbers in circulation are user reports. The MacRumors thread cited above reported roughly 40 to 55 MB/s on a peer-to-peer connection, rising to around 90 MB/s once the poster swapped in a proper USB-C data cable. Those are one person's observations on one pair of machines, not a benchmark, and you should treat them as an ordering rather than a prediction.

Wired Ethernet

An Ethernet path is the most boring and most predictable option, and boring is what you want here.

On modern laptops this means adapters or a dock at each end, or a Mac mini or Studio that has the port natively. Run both Macs into the same switch or router. Then, critically, turn Wi-Fi off on the source Mac, because otherwise Migration Assistant may still choose the peer-to-peer path per Apple's own documented behaviour.

Gigabit Ethernet is a 1 Gbps link, which is a hard ceiling but a stable one. Stability is what makes the time estimate usable and what stops the transport from flipping mid-transfer.

A Thunderbolt Cable Between the Two Macs

This is the fastest supported path for a direct Mac-to-Mac migration, and Apple's own hardware guides nudge you towards it. The MacBook Air user guide for macOS Tahoe 26 says that although you can transfer wirelessly by putting both computers on the same Wi-Fi network, it is often faster to connect the two Macs directly with a Thunderbolt or Ethernet cable. Oakley is more specific: connect them back to back with a good Thunderbolt 4 cable, or migrate from a backup on a Thunderbolt 3 SSD.

Two things go wrong here, and both are avoidable.

The cable. A USB-C connector does not make a cable a Thunderbolt cable. The charging cable that shipped in the box with a MacBook carries power and USB 2 data. That was the root cause in the MacRumors thread above: the migration was slow because a charge cable was in use, and it sped up substantially once a real data cable replaced it. Look for the lightning-bolt icon moulded into the connector housing, or a cable explicitly sold as Thunderbolt 3, Thunderbolt 4, Thunderbolt 5, or USB4.

The interface. Two Macs connected back to back over Thunderbolt get an IP-over-Thunderbolt interface called Thunderbolt Bridge. Glenn Fleishman's Macworld guide to Migration Assistant over Thunderbolt, published 7 April 2023, walks through confirming Thunderbolt Bridge is present and connected in Network settings, and notes that Migration Assistant's transfer screen has a Connection Details control telling you which link it actually chose. Use it; it converts a guess into a fact.

You can confirm the interface exists from Terminal on either Mac before you begin:

networksetup -listallnetworkservices

Look for a Thunderbolt Bridge entry in the list. If it is absent, add it in System Settings → Network using the ellipsis menu before starting the migration.

From a Time Machine Backup or an External Clone

This is the method that most people should reach for first when a direct migration has already failed once, and it is underrated as a first choice.

Migration Assistant accepts a Time Machine backup as a source. Apple's Restore your Mac from a backup article, last published 10 November 2025, documents the flow, and it is covered step by step later in this article.

Oakley confirms the source does not have to be Time Machine specifically: migration from a backup should work correctly whether it was created by Time Machine, Carbon Copy Cloner, SuperDuper, or any other good utility. What matters is that it is a volume-level backup at the root of a disk. Bombich Software, the developer of Carbon Copy Cloner, is explicit that a backup living inside a folder on a backup volume will not be accepted by Migration Assistant, and recommends writing a new backup of the startup disk directly to the root of a locally attached disk so you have a compatible source.

Why this method wins so often: there is no second live Mac in the loop, so nothing has to stay awake, stay on power, or negotiate a network. The source is a local disk, so throughput is bounded by the enclosure and the bus, both of which are stable. If it fails halfway you restart it without touching the old Mac at all. And you needed a current backup before doing any of this anyway.

If you do not have a backup strategy in place, fix that before you migrate rather than after; our Mac backup strategy guide for 2026 covers what a defensible setup looks like, and the Time Machine troubleshooting guide covers the failure modes worth clearing before you rely on a backup as a migration source.

From a Windows PC

Migration Assistant handles this too, with a Windows-side helper. Apple's Transfer from PC to Mac with Migration Assistant article, published 23 June 2026, specifies Windows Migration Assistant 3.0.2.1 for migrating from Windows 10 or later to macOS Tahoe 26, Sequoia 15, or Sonoma 14. Older macOS versions need older builds: 2.4.5.0 for Ventura 13 and Monterey 12, 2.3.1.0 for Big Sur 11. Downloading the wrong one is the most common reason this fails outright.

The requirements differ from the Mac-to-Mac case in one notable way: Apple states the two computers must be near each other with Wi-Fi and Bluetooth turned on, and warns that a PC without Bluetooth Low Energy may need a USB Bluetooth adapter. If the Mac runs macOS 13 or earlier, Apple additionally requires both computers on the same network or connected directly with an Ethernet cable.

Apple documents exactly what lands where in a table on that page: Outlook and Windows Mail accounts to Mail, contacts to Contacts, appointments to Calendar, Outlook tasks to Reminders on macOS 13 or later, media to the corresponding Apple apps, and bookmarks from Chrome, Edge, Firefox, Internet Explorer and Safari into Safari. Non-system files from the C drive land in the Shared folder inside your home folder, which Apple notes requires running Windows Migration Assistant while logged in to the PC as an administrator.

Two limitations. Windows applications do not come across, because there is no equivalent binary to move. And per the Mac User Guide, network settings and passwords are not transferred from a PC.

The Comparison Table

Method	Setup effort	Predictability	What it requires	Use it when
Thunderbolt cable, Wi-Fi off on source	Medium	Highest of the direct methods	A real Thunderbolt or USB4 cable; both Macs awake and on power	Both Macs work, you want the fastest direct path
Wired Ethernet, Wi-Fi off on source	Medium	High	Adapters or a dock at each end, plus a switch or router	Thunderbolt is not available; you want stable and boring
Time Machine backup on an external disk	Low	Highest overall	A current volume-level backup at the root of a disk	Direct migration has failed, the old Mac is dead, or you want the calmest option
Clone from Carbon Copy Cloner or SuperDuper	Low	High	Backup written to the root of a locally attached disk	You already run one of these tools
Infrastructure Wi-Fi, both Macs on the router	Lowest	Low	Nothing extra	Small transfers only, or nothing else is possible
Peer-to-peer Wi-Fi, the automatic default	Lowest	Lowest	Nothing, which is the problem	Avoid deliberately; this is what you get by accident
From a Windows PC	Medium	Medium	Windows Migration Assistant 3.0.2.1, Bluetooth LE	Switching from Windows

Share Disk Is Not Target Disk Mode

This is where most published advice about moving to a new Mac is simply wrong, and it has been wrong for years.

Why Holding T Does Nothing on an Apple Silicon Mac

Target Disk Mode is an Intel feature. Apple's Mac User Guide page on the subject is unambiguous about its scope, opening with a definition that names the architecture: you can connect an Intel-based Mac to another Mac so that the Intel-based Mac appears as an external hard disk, known as target disk mode. The instructions that follow are for the Intel machine: if the computer is off, start it up while holding the T key, or if it is on, use System Settings → General → Startup Disk → Restart in Target Disk Mode. When it starts up, a disk icon appears on the desktop of the other computer.

That same Apple page then redirects Apple silicon owners elsewhere in its second paragraph, stating that you can also transfer files between a Mac with Apple silicon and another connected Mac by starting up the Mac with Apple silicon in macOS Recovery.

There is no T-key path on Apple silicon. These Macs do not read startup key combinations at all; the whole startup-options flow moved to the power button. Holding T on an M-series Mac produces nothing.

One nuance explains where the confusion comes from. Apple's own Migration Assistant instructions do still mention the T key, but scoped very narrowly: the Mac User Guide's section on transferring from a Time Machine backup or other storage device says you can transfer from another Mac running OS X 10.8 or earlier connected with a Thunderbolt cable, and only in that case tells you to hold T. That is about machines from 2012 and earlier. Copying it out of context is how the myth propagates.

There is also a cable constraint on the Intel path that people miss: Apple's target disk mode page notes that if either computer has macOS 11 or later installed, you must connect them with a Thunderbolt cable. A plain USB-C cable is not sufficient.

How to Actually Use Share Disk

The Apple silicon replacement is called Share Disk, and it lives inside macOS Recovery. Apple's macOS Tahoe 26 Mac User Guide describes it as transferring files between a Mac booted into macOS Recovery and another Mac by sharing a volume and connecting the two computers with a USB, USB-C, or Thunderbolt cable. Note that the accepted cable list here is broader than the Intel target disk mode requirement.

The exact procedure, following Apple's documented steps:

1. Connect the two computers with a USB, USB-C, or Thunderbolt cable.
2. On the Mac whose disk you want to share, choose Apple menu → Shut Down and wait until it is fully off.
3. Press and hold the power button until the system volume and the Options button appear, then click Options and click Continue.
4. If asked, select a volume to recover, click Next, then select an administrator account, enter its password, and click Continue.
5. In the Recovery app, choose Utilities → Share Disk.
6. Select the volume you want to share, then click Start Sharing.
7. On the other Mac, open a Finder window and click Network in the sidebar under Locations.
8. Double-click the Mac that has the shared disk, click Connect As, select Guest, then click Connect.
9. Transfer the files.
10. When finished, eject the volume on the other Mac, click Stop Sharing in the Share Disk app, then choose Share Disk → Quit Share Disk.

If Apple's documentation for your macOS version differs from these steps, follow Apple's version; this is transcribed from the macOS Tahoe 26 edition of the Mac User Guide as published at the time of writing.

What the Other Mac Actually Sees, and Why It Matters

This is the part that gets glossed over everywhere, and it is the whole ballgame.

Target Disk Mode presented a block device. The old Mac genuinely appeared as an external hard disk, with a disk icon on the desktop of the other computer, addressable by Disk Utility and by anything else that expects a real volume.

Share Disk presents a network share over the cable. Apple's own steps prove it: you find it under Network in the Finder sidebar, not on the desktop, and you authenticate to it with Connect As → Guest. It is a file-sharing session that happens to be running over a Thunderbolt or USB link rather than over Ethernet.

That distinction is not academic. It changes which tools can consume it.

Why Share Disk Is Not a Migration Assistant Source

Because Share Disk hands you a network file share rather than a startup disk, Migration Assistant does not appear to accept it as a migration source, and there is a documented community report of exactly this.

Two Feedback reports filed on 29 January 2022, mirrored publicly on Open Radar as FB9864910 and FB9864933, describe it precisely. The reporter connected two 14-inch MacBook Pro machines with an 0.8 m Apple Thunderbolt 3 cable, put the source into Share Disk from Recovery, and ran Migration Assistant on the destination. Migration Assistant reported Looking for sources… forever. The link itself was fine — Finder on the destination could browse the network and connect to the source — and the reporter observed that the shared disk was available over AFP across the Thunderbolt connection. The second report asks Apple to at least detect and reject the configuration instead of leaving the user waiting. Both are listed on Open Radar with status Open.

Two honest caveats. Those reports are from January 2022 against macOS 12.2, and I have found no source confirming or refuting the behaviour on macOS 26. Apple's Mac User Guide does list a disk on the same network among accepted sources, which sits awkwardly against the report. My inference, labelled as inference: Migration Assistant's discovery looks for a mounted startup volume or a live Mac running Migration Assistant, and an AFP share presented by the Recovery environment is neither.

The practical consequence is the same either way. Do not plan your migration around Share Disk. Use it for what Apple documents it for: hand-copying files off a Mac you cannot boot normally. If you want a cable-speed migration, connect two running Macs and let Migration Assistant use the Thunderbolt link directly, or migrate from a backup on an external disk.

Before You Start: The Checklist That Prevents Most Failures

Most migration failures are configuration problems that were already present before anyone clicked Continue. This list is drawn from Apple's documented requirements plus the failure modes above.

First, preserve your fallback: Make a current backup of the source Mac and any data already on the destination, including files created since a failed attempt. Verify that the important files you need are recoverable before cleanup, account removal or replacement.

From Apple's documentation:

• Install all available macOS updates on both Macs. Apple is explicit that the two Macs do not need to be on the same version of macOS, only that each is up to date for whatever version it runs.
• If either Mac is a laptop, connect it to power. The Mac User Guide states this directly; the consumer support article does not, which is one reason people miss it.
• Apple advises temporarily turning off antivirus, firewall and VPN software until the transfer is done. Use a trusted connection and re-enable those protections on both Macs when migration finishes or you stop troubleshooting, before normal use. On a managed Mac, get IT's guidance first; do not bypass enforced controls.
• If either Mac is running OS X El Capitan or earlier, or you are not sure, also connect both to the same Wi-Fi network.

From the mechanism, not from Apple:

• Turn Wi-Fi off on the source Mac once you have a wired path in place. This is the direct consequence of Apple's own statement that a peer-to-peer Wi-Fi connection is established unless Wi-Fi has been turned off on the source Mac.
• Verify the cable is a data cable, not a charge cable.
• Disable sleep on both Macs for the duration. System Settings → Lock Screen and System Settings → Displays for the screen; on a laptop, keep the lid open or keep it on power with an external display attached.
• Check free space on the destination. Migration Assistant calculates the source size for you, but it does that after you have already committed to the setup.
• Review cleanup candidates only after backing up. Restore any needed items from the Trash and include them in a verified backup before emptying it; do not assume the Trash is backed up. Emptying the Trash permanently deletes its contents. Skip cleanup if you are unsure.
• Quit everything on the source Mac and let any Photos or Mail indexing finish before starting.
• Note down the source Mac's short user name. You will need it if the destination already has an account.

Running Migration Assistant Step by Step

On the New Mac

If the Mac is showing Setup Assistant, migration is part of that flow and you do not open anything separately. Otherwise, open Migration Assistant from System Settings → General → Transfer or Reset → Open Migration Assistant, or from the Utilities folder, and authenticate as an administrator.

When asked how you want to transfer, choose the option to transfer from a Mac, Time Machine, or startup disk, then click Continue.

On the Old Mac

Open Migration Assistant, click Continue, and when asked how you want to transfer, choose the option to transfer to another Mac, then click Continue.

The old Mac now sits waiting. It has quit your apps and logged you out to do this, which is expected.

Pairing and the Security Code

On the new Mac, select the icon of the old Mac from the list and click Continue. Both machines display a code. Confirm the codes match, then click Continue on the old Mac.

If the old Mac never appears in the list on the new Mac, that is a discovery problem, not a transfer problem, and the causes are almost always in the checklist above: a firewall or VPN still running, the two Macs on different networks, or a source that has gone to sleep.

The Calculation Phase

Migration Assistant now calculates how much storage space is used by all of your information, including applications, user accounts, files, folders, and settings. Apple's instruction is simply to wait for the calculation to complete.

On a machine with a large Photos library, a big Mail store, or developer directories full of small files, this phase can itself take a long time and it does not show a meaningful progress indicator. It is walking the filesystem. This is not the stage to panic at.

Choosing What to Transfer

Select the checkbox next to each category you want, or use the disclosure arrow next to a category to select specific items inside it. Expand each User account to select its Documents, Pictures and other personal folders; Other Files & Folders alone is not a substitute. This is where you deselect Applications if you decided on the middle path earlier.

Passwords and the Authorize Prompt

Three prompts can appear here and each means something specific:

• Transferring an administrator account. You are asked to click Set Password and set a secure password. Apple's warning is worth repeating: remember it, because you will need it to log in to that account on the new Mac.
• Transferring a standard account. A temporary password is assigned and shown on screen. Write it down. The user enters it at first login and is then prompted to set their own.
• Being asked to Authorize. If Migration Assistant asks for the password of an existing user who is already authorised on your new Mac, click Authorize and enter that account's password. This is the FileVault and secure-token authorisation path, and it is why you want to know the credentials of the account already on the destination machine before you start.

While It Runs

Apple's own expectation-setting sentence appears in both the Mac-to-Mac and the Time Machine article, word for word: large transfers might need hours to complete, and might seem to pause occasionally.

When it finishes, the Mac User Guide says the computer restarts, and that a migration summary is shown if issues were found — for example if documents could not be transferred or incompatible software was detected. Read that summary. It is the only structured report you get, and people close it reflexively.

Reading the Progress Bar Honestly

A Possible Model of the Phases

The table is an explanatory model, not an Apple-documented sequence or a way to diagnose a particular transfer. Small-file or metadata work can be one reason for a slow final stage.

Phase	What you see	What is happening	Normal duration
Discovery	Looking for sources	Both Macs advertising and listening on the chosen transport	Seconds to a couple of minutes
Calculation	Calculating, with no useful progress indicator	Walking the source filesystem to total up bytes and items	Minutes on a clean machine; much longer on a large Photos or Mail store
Bulk transfer	Progress bar moving steadily, estimate roughly stable	Large files streaming at close to link rate	The bulk of the wall-clock time on a big transfer
Small-file tail	Progress bar near the end, estimate collapsed to a small number and stuck	Enormous numbers of tiny files being created one at a time	The part that surprises people, and the part where they intervene

Why the Estimate Collapses Near the End

Apple has never documented how Migration Assistant computes its time estimate, and Apple has never acknowledged the specific About 1 minute remaining behaviour in any support article I can find. The closest Apple comes is the sentence quoted above about large transfers needing hours and seeming to pause occasionally. Everything that follows is my inference from how file copying works, and it should be read as inference rather than as documented behaviour.

One possible model is a bytes-based estimate: the calculation phase produces a total byte count, and remaining time could be extrapolated from bytes moved per unit time. This is not a verified description of Migration Assistant's algorithm.

That model works well during the bulk phase, because the bulk phase is dominated by a small number of large files. A 4 GB disk image, a video, a Photos library original: these stream at close to the link rate, and bytes-per-second is a good description of what is happening.

A possible late-stage workload is small-file and metadata work involving ~/Library/Caches, Mail files, Photos library metadata, browser profiles, node_modules trees or .git objects. These can involve many small files, but the progress screen does not establish that this is what your transfer is doing.

Every one of them costs a fixed amount of work that has nothing to do with its size. The destination has to create the file, copy extended attributes and any ACLs, set ownership and permissions and timestamps, and — over a network transport — complete at least one round trip. When the average file is four kilobytes, that fixed per-file cost is the entire cost. Throughput stops being a bandwidth question and becomes a files-per-second question, and files-per-second is one to three orders of magnitude worse in effective bytes-per-second terms.

In that model, a bytes-based estimate could understate the time needed for many small file operations. It does not establish how much work remains or how long a particular transfer will take.

An estimate of one minute remaining that persists for an hour does not prove that the migration is healthy or that it has failed. Avoid interrupting it based on that display alone; check both Macs for errors and confirm their power and connection first.

When It Is Genuinely Stuck, and What to Do

Check Progress, Power, Connections and Errors

The time estimate alone is not a health indicator. Apple does not publish its calculation method, and a changing workload is only one possible explanation for an inaccurate estimate.

The transferred-bytes figure and, where visible, the item count can show ongoing activity. If they are changing and neither Mac shows an error, allow the transfer to continue. A static counter alone does not establish failure.

There is no Apple-documented one-hour failure threshold. Apple says large transfers may take hours and appear to pause. Allow ample time, check both Macs and troubleshoot the connection before deciding whether to retry.

The Escalation Ladder

Work down this list in order. Do not skip to the bottom.

1. Allow ample time. Large transfers may take hours and appear to pause. Neither an unchanged estimate nor a static byte counter, even for an hour, is proof of failure.
2. Confirm both Macs are awake and on power. A sleeping source Mac stalls the transfer without any error on the destination. Nudge the trackpad on the source, do not click anything.
3. Confirm the link is still up. If you are on a cable, check that it has not been knocked loose. If Migration Assistant's transfer screen offers Connection Details, check which transport it is currently using; it may have silently downgraded.
4. Check the source Mac's screen. Migration Assistant on the source sometimes shows an error dialog that never propagates to the destination, including the startup networking error message described below.
5. Reassess after troubleshooting. If you fixed a power or connection problem, allow time for progress to resume. A fixed waiting interval cannot determine whether the transfer has failed.
6. If an explicit error occurs, or you decide to retry after troubleshooting, use Migration Assistant's cancel or stop control if available. Avoid cutting power as a first response; cancellation does not guarantee a complete destination account. Preserve your data before retrying.
7. Preserve the incomplete account before retrying. If a failed attempt created a disposable account, first verify your source backup, back up any destination-only files and confirm the account contains no unique data. If you then remove it in System Settings → Users & Groups, preserve its home folder as a disk image or leave the folder in place. Otherwise retain the account and resolve Migration Assistant's account-name prompt; deletion is not required.
8. Change transport and retry. If it failed on wireless, go wired. If it failed wired, go to a Time Machine backup.
9. Migrate from a backup instead. This is the fallback that actually works, and it is exactly what resolved the Tahoe case on Apple's community forums.

The One Situation Where Waiting Is Wrong

If the source Mac is displaying an actual error dialog, waiting accomplishes nothing. The reported example is a user on the Apple Support Communities in September 2025 migrating from an M1 Mac mini to an M4 Mac mini, both on macOS Tahoe. After the security codes matched, the source machine displayed: Unable to use this machine for migration. A startup networking error occurred. Please restart this machine and try again later. The poster reported the same failure over Ethernet, over Wi-Fi, and over a direct Thunderbolt connection. Two days later they posted the resolution: back up the source Mac to an external drive with Time Machine, then migrate from that backup.

That is a community report on one pair of machines, not a confirmed Apple bug with a documented fix, and I have found no Apple acknowledgement of it. But the escalation it demonstrates is the right one. When the direct path fails on every transport, stop trying transports and change the source.

Migrating From a Time Machine Backup Instead

The Steps

Following Apple's Restore your Mac from a backup article:

1. If the new Mac needs macOS reinstalled for any reason, do that first.
2. Connect the Time Machine backup disk and make sure it is powered on.
3. Open Migration Assistant, or use the migration step inside Setup Assistant.
4. Choose the option to transfer from a Mac, Time Machine, or startup disk.
5. Select the backup disk. Apple notes it might take a few moments to appear; do not conclude it is missing after ten seconds.
6. Select a backup. If Continue is dimmed, or you want an older backup than the one shown, click the disclosure arrow next to the displayed backup and pick from the list.
7. Wait for the calculation, choose your categories, and proceed as with a Mac-to-Mac migration.

One Thing Apple Explicitly Tells You Not to Do

There is a Time Machine System Restore option inside macOS Recovery, and it is the wrong tool for setting up a new Mac. Apple flags this directly in the Mac User Guide's macOS Recovery page with an Important note: only use your Time Machine backup to restore information to the computer that is the source of the backup, and if you want to transfer information from this Mac to a new computer, quit macOS Recovery, restart, and use the Migration Assistant app in macOS.

Time Machine System Restore restores a whole system to the machine it came from. Migration Assistant moves your data onto a different machine's freshly installed system. Using the former to set up a new Mac is a category error.

Claiming the Backup Afterwards

After migrating, when you connect the same backup disk to the new Mac, macOS offers to claim the existing backup history for the new machine. Howard Oakley covers this in detail: if you claim the backups, they become part of the new Mac's backup history, but they stop being usable by the old machine. He also notes that the tmutil inheritbackup command, which had stopped working with APFS backups, worked again as of macOS Sequoia 15.1.

If you intend to keep using the old Mac and its backup history, do not claim. If the old Mac is being sold or retired, claiming avoids a fresh full backup. The graphical prompt is the supported route; the exact tmutil inheritbackup argument form has changed across APFS revisions, so I am not going to print an invocation I cannot verify on macOS 26.

What Does Not Come Across, and Your Post-Migration Checklist

Migration Assistant moves files. It does not move state that lives outside files, and it does not move state that is bound to hardware. Here is what reliably needs attention afterwards.

Licences and Activations

Migration Assistant does not handle software licensing. Applications that key their activation to a hardware identifier, a machine fingerprint, or a per-device activation slot on a vendor server will treat the new Mac as a new installation. Depending on the vendor that means re-entering a key, signing in again, or deactivating the old machine first to free a seat.

The practical instruction is the boring one: before you wipe or sell the old Mac, deactivate everything on it. Adobe, Microsoft, most audio and video plugin vendors, and most professional CAD and statistics packages all have a deactivate or sign-out step, and doing it after the machine is gone is much harder than doing it before.

Mail

Apple documents this one directly: Migration Assistant transfers your email, but to access it you might first need to set up your email account again in your email app. Expect to re-authenticate accounts, and expect a re-index that can run for hours and that will make Spotlight and Mail search unreliable until it finishes.

Homebrew and Command-Line Tooling

This is the biggest single source of post-migration confusion for developers, and the cause is architectural.

Homebrew's prefix on Apple silicon is /opt/homebrew. On Intel it was /usr/local. Migration Assistant, per Oakley's description, attempts to migrate well-known hidden folders including /usr/local. So an Intel-to-Apple-silicon migration can land you with an entire Intel Homebrew tree at /usr/local on a machine whose native prefix is /opt/homebrew, with /usr/local/bin still on your PATH from a migrated shell profile.

Homebrew's own Common Issues documentation addresses the symptom, instructing you to delete a leftover /usr/local/bin/brew before reinstalling if one remains from the old Mac.

Apple-silicon-to-Apple-silicon is much better. Homebrew maintainer Gromgit, responding in the project's discussion forum, described such migrations of Homebrew and installed formulae and casks as generally seamless, with the caveat that a large jump in macOS versions may require reinstalling some formulae, that you should check whether services configured to launch at login still do, and that security-critical casks such as macFUSE should be manually reinstalled so the new machine can grant them the permissions they need.

The clean approach, and the one worth the twenty minutes it costs, is to capture a manifest on the old Mac before you migrate:

brew bundle dump --describe --file=~/Brewfile

Then on the new Mac, install Homebrew natively and replay it:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> ~/.zprofile
brew bundle install --file=~/Brewfile

Every binary is then a current native build for the correct architecture, rather than whatever your old machine happened to have.

System Extensions, VPN Clients, and Security Agents

Anything that installs a system extension, a network extension, a launch daemon, or a privileged helper needs a fresh install on the new Mac. The files may migrate, but the approvals do not: macOS asks the user of this machine to approve a system extension, and that approval is per-installation.

VPN clients, endpoint security agents, backup agents with privileged helpers, virtual audio devices, printer and scanner drivers, and filesystem drivers such as macFUSE all fall into this category. The symptom is consistent and misleading: the app launches and looks fine, but its background component silently does nothing.

You can inventory what is actually loaded on the new Mac afterwards:

systemextensionsctl list

That prints the registered system extensions and their enablement state. If something you expect is missing, or is present but not enabled, reinstall the app from a current installer rather than trying to re-approve the migrated copy.

Apple's Startup Security Utility, reachable in macOS Recovery under Utilities → Startup Security Utility, is where legacy kernel extensions are governed on Apple silicon. Full Security is the default; allowing user management of kernel extensions from identified developers requires dropping to Reduced Security. If an old app needs a kernel extension, this is a decision you have to make deliberately on the new machine — it is not something migration carries across.

Docker and Virtual Machines

Docker Desktop is a reliable casualty. The docker/for-mac issue tracker has a long-standing report that using Migration Assistant causes Docker to fail to start until the relevant Library/Group Containers directory is manually deleted, and a separate failure mode where the daemon will not start if the home directory user name changed during migration. Contributors also note that on Apple silicon, tools like colima or limactl migrated into /usr/local/bin from an Intel Mac are the wrong architecture.

Treat container and VM state as something you rebuild, not something you migrate. Export what you need, reinstall the tooling natively, and re-pull images.

Rosetta and Intel-Only Apps

The timing here is unusually consequential in 2026.

Apple announced at WWDC 2025 that macOS 27 would be the last release with full Rosetta 2 support, with only a limited subset retained from macOS 28 onwards for older, unmaintained game titles that depend on Intel frameworks. Since macOS 26.4, the system notifies you when you launch an app that requires Rosetta 2. macOS 27 Golden Gate, announced at WWDC in June 2026 and expected in September 2026, is Apple silicon only and drops every Intel Mac.

The consequence for migration: every Intel-only binary you carry onto a new Mac today has a defined shelf life. Migration Assistant will bring them, and per Apple's own note in the Mac User Guide, incompatible apps or apps with a newer version already installed may not be transferred or may not be usable. Gant's observation is that Migration Assistant flags Intel-only apps on Apple silicon rather than refusing the migration outright.

The right time to audit is before you migrate, not after, because the audit tells you which applications you should simply not bring. Our Intel app audit guide for the end of Rosetta 2 walks through the methods for producing that list.

The Post-Migration Checklist

Item	Action
Migration summary	Read it before dismissing; it lists what could not be transferred
FileVault	Check status; save and verify the new Mac's recovery method separately, and retain the source Mac's recovery key until it is intentionally erased and no longer needed for recovery
Mail	Re-add accounts, let indexing finish before judging search
iCloud and Apple Account	Sign in, then confirm the new Mac appears in your device list
Licensed software	Reactivate; deactivate on the old Mac before disposing of it
Antivirus, firewall, VPN and security agents	Reinstall agents from current installers as needed; re-enable and verify all temporarily disabled protections on both Macs before normal use
System extensions	Verify with systemextensionsctl list
Homebrew	Reinstall natively at /opt/homebrew, replay a Brewfile
Docker and VMs	Reinstall; rebuild container and VM state
Time Machine	Decide whether to claim the old backup history, then verify the first backup completes
Login items	System Settings → General → Login Items & Extensions; prune what migrated
Old Mac	Keep it until important migrated files and apps are verified and a destination backup has completed. Only then follow Apple's retirement steps below

Before erasing the old Mac, keep a verified source backup and complete a backup of the new Mac. Erase All Content and Settings requires macOS Monterey 12 or later on Apple silicon or a Mac with the T2 Security Chip. For older Intel Macs or other unsupported setups, use Apple's alternative retirement instructions. Erasure removes the old Mac as a fallback.

Once the machine is working, it is worth doing the general new-Mac configuration pass as well; the first 24 hours setup checklist covers the settings worth changing while you are already in System Settings.

Special Cases

Intel to Apple Silicon

Apple supports this migration and does not require matching macOS versions — its stated requirement is only that each Mac is up to date for the version it runs. What changes is the software.

Recommended approach: migrate user accounts, Other Files & Folders, and settings; deselect Applications; reinstall applications from current installers. This gets you native builds everywhere and sidesteps both the Rosetta countdown and the /usr/local problem. It costs an evening.

If you do migrate applications, plan on auditing them afterwards and replacing the Intel-only ones.

FileVault Before, During, and After

FileVault encrypts the volume, not the files as objects. Migration reads decrypted content from the source and writes it to the destination. Glenn Fleishman's Macworld piece on this describes the awkward outcome: it is possible to end up in a state where macOS believes FileVault is enabled when it is not, precisely because the migration moved unencrypted data rather than the encrypted container.

The practical sequence:

1. On the source Mac, know your login password. FileVault does not block migration, but you need to be able to log in.
2. On the destination, set up an administrator account through Setup Assistant, then migrate.
3. Afterwards, check FileVault's actual state rather than assuming it:

fdesetup status

4. If it is off, turn it on in System Settings → Privacy & Security → FileVault and record the new recovery key somewhere durable.
5. The old Mac's recovery key does not unlock the new Mac. Keep it securely until the source Mac is intentionally erased and you no longer need to recover its encrypted data. Save and verify the new Mac's recovery method separately. Apple explains the recovery options and warns about losing access without a usable password or recovery key.

There is one genuine gotcha with multiple accounts. Mac admins have long reported that Migration Assistant does not necessarily grant a secure token to every account it creates, which means a secondary account can exist but be unable to unlock a FileVault-encrypted disk at boot. Apple does not document this behaviour, so treat it as a field observation rather than a specification. The defensive move is cheap: if you migrate several accounts onto a FileVault machine, log in to each one and confirm it can unlock the disk after a restart, before you retire the old Mac.

Accounts With the Same Short Name

This is one of the few genuinely well-documented edge cases, and Apple handles it with an explicit prompt.

If an account with the same name already exists on the new Mac, Apple's support article says you are asked to choose between two options:

• Replace the account on the new Mac with the account from the old Mac. Apple notes you might also have the option to keep a copy of the replaced account's data by moving it to the Deleted Users folder, where you can access it later.
• Rename the old account before transferring it, which keeps both accounts so you can log in to them separately.

Before choosing Replace, back up any destination-only files and confirm that nothing unique will be lost; even a recently created account can contain new work. Rename keeps both accounts. If you are unsure, retain both rather than assuming the destination account is disposable.

The way to avoid the choice entirely is to migrate during Setup Assistant, before any account exists. If you are migrating later, the cleanest approach is to create the Setup Assistant account with a deliberately different short name — something like admin — so that the migrated account arrives at its original name with no collision, and you keep the throwaway admin account as a spare with a secure token.

Managed and Work Macs

If the new Mac is enrolled in a device management service, do not improvise. Apple's Managed Migration Assistant, documented in the Platform Deployment guide, lets an organisation control what transfers: which subfolders inside the home folder are required, which are excluded, which user accounts are not offered for migration at all, and whether system-level privacy settings come across. Its requirements are macOS 15 or later on the source Mac, macOS 26.4 or later on the new Mac, and the new Mac registered in Apple School Manager or Apple Business Manager and assigned to a management service.

If that is your situation, the migration may be shaped by policy in ways that will not be obvious from the UI, and the administrator gets a report afterwards including the date, time, amount of data transferred, and whether any files could not be migrated. Ask before you start.

Migrating Into a Mac You Have Already Been Using

Migration Assistant works into any Mac, not just a new one, but the situation is more fragile because the destination already has state. Back the destination up first — even a recently configured destination can contain unique files — and be deliberate about the account-collision choice above, because Replace on a machine you have used for six months means something very different from Replace on a machine you unboxed this morning.

Troubleshooting Common Issues

Migration Assistant Never Finds the Other Mac

Problem: The new Mac shows Looking for sources… indefinitely, or the old Mac never appears in the list.

Solution: This is a discovery failure, not a transfer failure, and Apple's prerequisites cover most causes. Temporarily turn off antivirus, firewall and VPN software only for the migration on a trusted connection, following IT's guidance on managed Macs. Re-enable protections on both Macs when the transfer finishes or you stop troubleshooting, before normal use. Confirm each Mac is at the correct step: the new one on from a Mac, Time Machine, or startup disk, the old one on to another Mac. Confirm both are awake, on power, and close together. If either Mac runs OS X El Capitan or earlier, put both on the same Wi-Fi network. And if the source is sitting in Share Disk mode from Recovery, that is the configuration reported to hang here indefinitely — boot it normally and run Migration Assistant on it instead.

The Transfer Is Running at Wireless Speed Despite a Cable

Problem: You connected a Thunderbolt cable but the transfer is crawling.

Solution: Two causes, in order of likelihood. First, the cable: a MacBook charging cable has a USB-C connector but carries only USB 2 data, and swapping it for a real Thunderbolt or USB4 cable was the fix in the MacRumors thread on this. Look for the lightning-bolt marking. Second, transport selection: turn Wi-Fi off on the source Mac, then use the Connection Details control on the transfer screen to confirm which link is actually in use, and verify Thunderbolt Bridge shows as connected in System Settings → Network.

It Says About 1 Minute Remaining and Has Said So for an Hour

Problem: The countdown collapsed to a small number and stopped moving, but the transfer has not finished.

Solution: A static estimate alone does not establish failure. Small-file or metadata work is one possible explanation, not a diagnosis or a documented description of the estimator. Check both Macs for errors and confirm their power and connection. Allow ample time for a large transfer; a static byte counter for an hour is not a failure threshold. If you decide to retry after troubleshooting, use the app's cancel control if available and preserve source and destination data first.

Unable to Use This Machine for Migration, a Startup Networking Error Occurred

Problem: After the security codes match, the source Mac displays this error and the migration never begins.

Solution: Reported on the Apple Support Communities in September 2025 by a user migrating between two Mac minis on macOS Tahoe, who saw the identical failure over Ethernet, Wi-Fi, and a direct Thunderbolt connection. The resolution posted in that thread was to abandon direct migration: back the source Mac up to an external drive with Time Machine, then migrate from that backup. There is no Apple acknowledgement of this specific error, so treat it as a community-reported failure with a community-verified workaround. Before switching to the backup route, restart both Macs and try once more. If temporarily disabling VPN or security software for that attempt, use a trusted connection, obtain IT guidance on managed Macs and restore protections as soon as the attempt ends.

The Migration Finished but the New Mac Is Slow and the Fans Are Running

Problem: Everything transferred, but the machine is hot and unresponsive for hours afterwards.

Solution: This is almost always post-migration indexing rather than a migration failure. Spotlight is indexing the newly written data volume, Photos is rebuilding its analysis database, and Mail is re-indexing its message store. On a large library that legitimately takes hours and is both I/O and CPU intensive. Leave the Mac plugged in, awake, and on the network, and judge its performance the following day rather than the same evening.

An App Launches but Its Background Component Does Nothing

Problem: A VPN client, backup agent, security tool, or virtual audio driver launches and looks normal but has no effect.

Solution: The application files migrated; the system-level approvals did not. System extensions, network extensions, and privileged helpers must be installed and approved on the machine they run on. Check what is actually registered with systemextensionsctl list, then reinstall the affected app from a current installer downloaded fresh rather than from the migrated copy. Approve the extension when macOS prompts, and check System Settings → General → Login Items & Extensions afterwards.

The Terminal Is Broken, or Commands Point at the Wrong Architecture

Problem: After an Intel-to-Apple-silicon migration, shell commands behave oddly, brew misbehaves, or tools report architecture errors.

Solution: A migrated /usr/local tree and a migrated shell profile are almost certainly the cause. Confirm the machine's architecture with uname -m, which reports arm64 on Apple silicon. Then follow Homebrew's guidance: remove any leftover /usr/local/bin/brew from the old Mac before reinstalling, install Homebrew natively so it lands at /opt/homebrew, and fix your shell profile so /opt/homebrew/bin comes first on PATH. Replay your package list from a Brewfile rather than trusting the migrated tree.

A Migrated User Account Cannot Unlock the Disk at Startup

Problem: FileVault is on, but a secondary migrated account is not offered at the pre-boot unlock screen.

Solution: This symptom alone does not establish a secure-token problem. Log in with an administrator account that can unlock the disk, then open System Settings → Privacy & Security → FileVault. If Enable Users appears, follow Apple's instructions to select the affected user and enter that user's login password. If the control is absent, or the Mac is managed, ask the administrator or Apple Support rather than guessing a token fix; managed configurations can also involve bootstrap tokens and volume ownership. Restart and verify that each intended user can unlock the disk before retiring the old Mac.

FAQ

Can I use Migration Assistant if the two Macs are running different versions of macOS?

Yes. Apple states directly that it is not necessary for each Mac to be using the same version of macOS, only that macOS is up to date on each one. In practice a very large version gap raises the chance that migrated applications behave oddly, which is why Howard Oakley advises migrating soon after buying the new Mac.

Does Migration Assistant erase or change anything on my old Mac?

No. Apple's support article states plainly that Migration Assistant does not delete information from your old Mac. Keep that fallback until you have checked important migrated files and apps and completed a destination backup. If you later retire it, use the supported erasure method for its model and macOS version, as described in the post-migration checklist.

How long should a migration actually take?

Apple publishes no throughput figures for any transport, so there is no official answer. Apple's only guidance is that large transfers might need hours. As one reference point, Howard Oakley reported that migrating from a Mac Studio M1 Max to a Mac mini M4 Pro, using a backup on a Thunderbolt 3 SSD, took under two hours.

Should I migrate during initial setup or afterwards?

During setup, if you know you want most of your old machine's contents. Migrating in Setup Assistant lets Migration Assistant create the account cleanly and avoids the same-short-name collision entirely. Migrating later works fine, but you will have to decide between replacing and renaming an account, and that decision has consequences.

Is it safe to force-quit Migration Assistant when it looks frozen?

An unchanged estimate or byte counter alone does not establish failure, even after an hour. Check both Macs for errors, power and connection problems, and allow ample time. If an explicit error occurs or you decide to retry after troubleshooting, use Migration Assistant's cancel control if available. Preserve your source backup and any destination-only files; retain the partial account unless it is confirmed disposable, and preserve its home folder if you remove it.

Can I migrate from an old Mac that will not start up?

Often, yes, but not through Share Disk. Migrate from a Time Machine backup or a volume-level clone instead, provided it sits at the root of a locally attached disk rather than inside a folder. If you have no backup and the Mac is Apple silicon, Share Disk from macOS Recovery at least lets you copy files off by hand.

Conclusion

Migration Assistant is not unreliable. It is under-specified, in the precise sense that the choice which determines almost all of your outcome — the transport — is made automatically, documented only in an IT deployment guide, and defaults to the worst of the four options unless you actively prevent it.

Three decisions carry the weight. Decide what you are migrating before you start, because deselecting Applications on an Intel-to-Apple-silicon move removes most of the post-migration pain for the price of one evening of downloads. Give Migration Assistant a wired path and turn Wi-Fi off on the source Mac, because Apple's own documentation says the two machines will establish a peer-to-peer Wi-Fi link unless you do. And when the countdown stalls, check progress alongside errors, power and connection status. Small-file work is only a possible explanation; neither the estimate nor a static byte counter, even for an hour, proves failure.

If the direct path fails twice, stop trying transports and change the source: back the old Mac up to an external disk and migrate from the backup. That removes the live second machine, the network, and the interactive session from the problem in one move, and it is the escalation that resolved the failures reported on Apple's own forums.

Whatever you do, do not hold T on an Apple silicon Mac. Target Disk Mode is an Intel feature and Apple's documentation says so in its first sentence. The Apple silicon equivalent is Share Disk, under Utilities → Share Disk in macOS Recovery, over USB, USB-C or Thunderbolt — and it hands the other Mac a network share rather than a disk on the desktop, which is exactly why it is a file-copying tool and not a migration path.

Related reading: Mac migration pitfalls from two real machines · Best Mac backup strategy for 2026