migration assistant stuck restoring from Time Machine

Hi julianpic,

Welcome to Apple Support Communities. With the inability of restoring your backup on a network-attached storage, we recommend to follow these steps:

If you can't back up or restore your Mac using Time Machine 

If Time Machine says that it can't use your backup disk to back up or restore your files, try these solutions.

Make sure that you're using a backup disk supported by Time Machine.

Unless you're using a network backup disk, make sure that your backup disk is connected directly to your Mac, not through a USB hub or other device.

If your backup disk is connected directly to your Mac, use Disk Utility to repair the disk.

If you're using a network backup disk, make sure that the network connection is good and your Mac is connected to the same network as the backup disk. If you completed a previous backup successfully, verify that backup: Press and hold the Option key while choosing Verify Backups from the Time Machine menu in the menu bar.

Make sure that the firmware of your backup disk is up to date. Check with the manufacturer of the backup disk for details.

If no other solutions work, start over: Erase your backup disk, then use Time Machine to select it as your backup disk again. 

That information is outlined in this helpful article: If you can't back up or restore your Mac using Time Machine

Following these steps may help.

Kind regards.

Thanks for following up.

Does the computer currently have an operating system installed? If not, let’s do that first following the steps found here: How to reinstall macOS - Apple Support

Next, for Migration assistant, you will want to have the Time Machine backup disk connected directly to the Mac, not connected through the network. Once that is done, follow the rest of the steps found here to move the information: Restore your Mac from a backup - Apple Support

Let us know if this helps.

julianpic,

You actually are not required to have the Time Machine backup directly connected to your Mac, based on Restore your Mac from a backup. But there may be several reasons why you're not able to restore your backup.

Is macOS currently installed on your Mac? If you need to reinstall macOS, do that before continuing: reinstall macOS

If the steps in Restore your Mac from a backup don't work, follow If you can't back up or restore your Mac using Time Machine. If those steps don't work or "If you need help, please contact Apple Support."

We hope those steps resolve the issue.