iMac stuck on 100 % progress bar I have a serious problem with my 2017 iMac running macOS Catalina BETA.  After a normal reboot the iMac loaded until the bar reached 100%. Then for hours nothing happens, it just stays at 100%.   

The things I tried:


Boot in Safemode - still hangs on 100%, can’t access Safemode
Reset NVRAM/PRAM - nothing happened 
Reset SMC - nothing happened 
Run First Aid on all disks - helped and discovered nothing
Uninstalled Google Chrome update in terminal - nothing happened
Tried to reinstall MacOS Catalina - not enough space on my disk 
Tried these commands: cd /Volumes/Macintosh\ HD/var/db/caches/opendirectory and mv ./mbr_cache ./mbr_cache-old - “no such file or directory”
Tried to boot in startup manager - still hung on 100%
Tried to run the Apple diagnostics - it said everything is fine
Single user mode with commands like mount-uw / - command not found
Let the iMac sit for a couple days - still hangs on 100%


And so on…
So, as you can see, I tried many things and nothing helped. Do you have a good solution or a advice/suggestion without erasing the disk?
Apple has a very good triage step that I follow even after doing a very good job like you in trying to eliminate things (or hope for a quick fix)


https://support.apple.com/en-us/HT204267 (always start with the basics)
https://support.apple.com/en-us/HT204156 (Which leads to general OS startup)
https://support.apple.com/en-us/HT207019 (which is the detailed - just updated and boot fails process)


Why not start down that path and this evening make a good last backup so you can proceed where it says erase and start over?


https://support.apple.com/en-us/HT204904 (The erase and start over process)