10.14.5 freezes after installing 10.15 on a partition

As an update, it seems that it was the installer profile that caused 10.14.5 to freeze. I reinstalled Catalina on an external drive, which went fine. I then rebooted under Mojave, with the external drive unattached. Mojave went right back to frequently, intermittent freezes. The last thing remaining of Catalina was the beta profile, so I removed my Mac from the beta group, and Mojave immediately began to behave itself.

Please check my full answer here on how to solve it

(I just posted it, and it solves that problem. if my answer is not showing yet to you, please wait for the moderator to aprove it and check back the link below in a few minutes)

https://forums.developer.apple.com/thread/117281

Hi prado, can you post your Solution somewhere on a blogpost, if it’s not approved? Thanks!

Yes, it is a big writeup, and it is still there for moderation, I ´ll try to be short here, freeze is caused by time machine localsnapshots, the full description is on my post there... I'll post it on some blog. Please check if this issue is you case: go into safe mode, open terminal, type the command: tmutil listlocalsnapshotdates

To fix you need to delete those local snapshots, one by one with the command: tmutil deletelocalsnapshots <snapshot item>

where 'snapshotitem' is those listed. Reboot, Catalina will work again