MacBook Air Migration Assistant 'Completing Transfer' taking 15 hours

MacBook Air Migration Assistant – 'Completing Transfer' for 15 Hours

The good news is that 15 hours does not necessarily mean something has gone wrong. Given that Migration Assistant has transferred approximately 2.7 million files and the progress bar is still moving, I wouldn't assume your new MacBook Air has frozen.

1. Is 15 hours normal?

It can be, particularly when migrating from a large Time Machine backup.

Several factors can contribute to the lengthy transfer:

• Millions of small files: Processing individual files takes considerably longer than transferring a few large files.
• Finalising the migration: Migration Assistant must also process user accounts, permissions, settings, applications and file metadata.
• External hard drive speed: A traditional mechanical hard drive (HDD) can be considerably slower than an SSD, even over USB-C.
• Time Machine backup structure: The backup contains extensive file and metadata information that must be examined and processed.

The fact that the progress bar is still moving is encouraging and suggests that Migration Assistant is continuing to work.

2. What should you do now?

My recommendation is to leave it running and avoid interrupting the migration.

• Keep the MacBook Air connected to its power adapter.
• Leave the external Time Machine drive connected.
• Don't restart, shut down or force-quit Migration Assistant.
• Check periodically whether the progress bar or file count is advancing.

Given that there is still movement, I would let it continue overnight, even if that means another 8–12 hours.

There is no published Apple maximum migration time, so 15 hours alone is not sufficient reason to cancel it.

3. When should you become concerned?

What you observe

Recommended action

Progress bar continues moving >> Keep waiting

File count increases >> Keep waiting

Progress bar pauses briefly >> Don't worry

No movement for several hours >> Investigate further

An error message appears >> Record it before taking action

The file count isn't necessarily a reliable indication of how close the migration is to completion.

Final processing can take a disproportionate amount of time.

If the progress bar and file count remain completely unchanged for several hours, I would contact Apple Support before attempting a forced restart.

Your original Time Machine backup should remain intact; Migration Assistant does not delete the source backup.

4. A couple of questions

To help assess whether 15 hours is reasonable in your circumstances:

1. Approximately how much data is being transferred (e.g. 256 GB, 512 GB, 1 TB)?
2. Is the file count still increasing, or has it been sitting at approximately 2.7 million for several hours?

My overall recommendation

Keep waiting for now. The combination of a large Time Machine backup, 2.7 million files and a progress bar that is still moving gives reasonable grounds to believe the migration is still working.

If this were my brand-new MacBook Air M5, I would leave it connected to power and the external drive and let it continue. I would much rather wait another night than interrupt a migration that might be close to finishing.

For further guidance, Apple's official instructions are available here:

• Restore your Mac from a Time Machine backup – Apple Support.

• Transfer to a new Mac with Migration Assistant – Apple Support.

48 hours is a very long time for Migration Assistant to be showing "Completing Transfer". Although transferring 2.7 million files can take a considerable amount of time, I would be reluctant to keep waiting indefinitely.

Apple does acknowledge that large transfers can take hours and may occasionally appear to pause. However, I would suggest checking whether your Mac is still actively working before deciding what to do next.

Here is what I would recommend:

1. Check whether the transfer is still progressing

If the progress bar is still moving, that is encouraging, but it doesn't necessarily mean that the transfer is making meaningful progress.

If possible, check whether the number of files transferred is increasing. If it has remained at 2.7 million for several hours, that would be a reason for concern.

2. Keep the Mac connected to power

If you decide to keep waiting a little longer, make sure the MacBook Air is connected to its charger. Leave the external Time Machine drive connected, and avoid putting the Mac to sleep or disconnecting anything.

3. If it appears stuck, I would consider restarting the migration

After 48 hours, if there has been no meaningful progress for several hours, I would be inclined to stop waiting and investigate.

I would not immediately force a shutdown unless the Mac is unresponsive. If Migration Assistant is still responding, use its available cancellation or exit option if possible.

A restart may be necessary if it has become completely unresponsive.

4. Check the Time Machine backup before trying again

The good news is that your Time Machine backup should remain intact on the external drive. Migration Assistant does not erase the original backup when transferring data to a new Mac.

If the migration fails, you can try again using the same backup.

Before doing so, I would check:

Whether the external drive is healthy and working properly.

Whether the USB-C cable and connection are reliable.

Whether the backup contains a very large amount of data.

Whether the new Mac has enough available storage for everything being transferred.

5. Contact Apple Support if it happens again

If a second migration also gets stuck at "Completing Transfer", I would contact Apple Support rather than repeatedly restarting the process.

You have a brand-new MacBook Air (M5, 2026), and Apple should be able to help determine whether this is a migration issue, a problem with the backup, or a software issue.

You can find Apple's official guidance here:

Restore your Mac from a backup - Apple Support

My personal recommendation would be to give it a little more time only if you can see genuine progress. If it has been sitting at the same number of files for many hours, I would stop waiting and investigate.

One important question:

When you say it has been going for 48 hours, is the progress bar actually moving forward, even very slowly, or has it remained in exactly the same position for the last several hours?

That would help determine whether I would continue waiting or recommend stopping the migration.

Apple's own guidance confirms that large migrations can take hours, but it does not suggest that a 48-hour completion phase is expected. 

Thanks for this - I will keep waiting and see how it goes.

Hi - it is still going - it has now been around 48 hours. Any suggestions?