macOS update "booted to Recovery" because "an error occurred migrating user data" on Big Sur/Monterey w/ multi-user Nix present #4531
Description
No need to triage this. Opening it for visibility/support. To keep this focused, I'll save detail/discussion for the related PR (#4532).
We've had several people with multi-user/daemon nix installs report trouble with macOS system updates. (Single-user installs have been the default for a while; if you don't know you have a multi-user install, you probably don't). You may also encounter this if you have nix-darwin installed (regardless of whether you have a single or multi-user Nix install).
Updates to 11.2 (and probably 11.1):
During the multiple-reboot phase of a system update, the system will boot into recovery and show the message:
Your computer booted to Recovery because a failure occurred during installation.
An error occurred migrating user data during an install.
Reinstall macOS to resolve the issue.
Updates to 11.3:
During the multiple-reboot phase of a system update, the system will boot into recovery and show the message:
If you do not know the password for an admin user, the reset operation requires resetting the passwords of all accounts on the system.
Set a password for each user on your Mac.
... long list of users including at least nixbld1-32 and your user account
Workarounds
- If you run into these issues during an update: Multiple users have reported getting around this problem without having to reinstall macOS or reset user passwords by simply rebooting again. Since this issue is likely to recur on your next update, you'll probably want to also apply the next workaround after rebooting.
- Nix now has a nixbld-user migration script that should let you skip this heartburn. Since the problem seems to recur on each update, you may want to apply this fix even if you've already installed the most recent update.
If you've been affected by this and want to report it to Apple, you can refer to the feedback I've filed: FB8997501