Failed update to 12.6

[endecotp]

Dear Experts,

I have just tried to update my M1 Mac mini from 12.5 to 12.6, and it has not gone well.

It is now in a state where applications (including Safari etc) do not start and the cursor is permanently a spinning rainbow. Menus don’t work.

I am able to ssh in, and top shows lsd using 100% CPU with its RAM ramping up to about 700 MB before dropping back to almost zero, over a period of about 15 seconds, and repeating ad infinitum.

It’s a reasonably vanilla development machine, with XCode installed and some homebrew things. I have Barrier installed to share keyboard and mouse, and time machine backs up to a Linux Samba server. Both barrier and time machine have misbehaved at various times and needed restarting. It has an external HDMI monitor, and during the update this was blank (no Apple logo and progress bar) for much of the time.

What is the best way to diagnose / resolve this?

Thanks for any suggestions.

 

[rpmurray]

Reboot in Safe Mode to see if it's anything third-party causing this?

Reboot into Recovery Mode to see if you can try re-installing the update?

 

[bobbyclobber49]

I had a challenge to update from 12.5 to 12.6. Seems the culprit was my external hard drives (2). Once I unplugged them the update went just fine.

 

[endecotp]

Thanks both for the comments. I decided to do something else and see if it would eventually resolve itself. After a wait, the 100% CPU lds process was joined by a 100% CPU mdsync process - and then eventually both finished. After another reboot the machine seems to be function enough for me to post this message (the previous one was from an iPad).

It's possible that the remote samba filesystem used for time machine is a factor; I have previously seen long-running mdsync processes that seem related to it, after macOS updates. It shouldn't really need to do spotlight indexing on the remote filesystem that's just used for time machine backups, should it? I wonder if I can disable that somehow?