I ran into a similar issue with a client system back in November. Since they were under MDM I was able to enable Remote Desktop and do some investigation while the machine was stuck. I discovered the following:
The system was hanging on the process "Installer Progress":
/System/Library/CoreServices/Installer Progress.app/Contents/MacOS/Installer Progress --showProgress
And tailing the system.log showed:
Nov 1 12:48:51 The-Host Installer Progress[104]: Unable to quit because there are still phases. The UI is not showing.
Nov 1 12:48:51 The-Host Installer Progress[104]: currentPhase = "<IASPPhase: 0x600001aed820: 'loginwindow Boot', percentage 4.8, delay -1>", phases = (
"<IASPPhase: 0x600001aed780: 'IOKit Boot', percentage 35.0, delay 0>",
"<IASPPhase: 0x600001aed840: 'ShouldHeal', percentage 36.1, delay 0>",
"<IASPPhase: 0x600001aed720: 'Heal', percentage 24.1, delay 0>",
"<IASPPhase: 0x600001aed820: 'loginwindow Boot', percentage 4.8, delay -1>"
)
Nov 1 12:49:47 The-Host loginwindow[146]: There is still an active connection
Nov 1 12:50:34 The-Host login[901]: USER_PROCESS: 901 ttys000
Rebooting the machine and repeating the investigation resulted in the same log event being repeated after each reboot. Leaving the machine for hours had no change to the condition. However, if I killed the Installer Progress process, the system resumed and the Finder loaded. The user was then able to work. Until they rebooted.
If you are not using an MDM and/or Remote Desktop is not already enabled, then you will need to enter Recovery Mode to resolve this.
What appears to correct this is to clear the contents of /Library/Caches/. com.apple.aned will not delete both it does not seem to be the issue. I also cleared the contents of /Library/InstallerSandboxes/. That was the first folder I cleared. But, after a reboot, the system continued to halt and prevent the Finder from loading. It was only after clearing the Caches folder that the startup worked as expected and the Installer Progress process stopped halting the load of the machine.
Boot into Recovery, mount the drive, and review the contents of your system.log. If you see the error above, you are likely experiencing the same issue. If so, try clearing the contents of /Library Caches and reboot the machine. Are you able to complete the login process and does the Finder load as expected?
Hope this helps,
Reid