COMPLETELY BEWILDERED! REALLY NEED SOME HELP WITH THIS, AT WITS END :
Wrote about this a few days ago. Installed to 2010 Mini which ran perfectly fine with build 18G103 on the internal HDD, until I ran the 2020-001 update. Produces endless beachballing, hangs, crashes, etc., BUT ONLY ON THE INTERNAL.
Runs perfectly well updated either on APFS (from Software Update) or HFS+ (by way of standalone/manual) on external drives. But as soon as I copy (with CCC) to the internal it becomes almost unusable. Have already done several reinstalls, but problem persists unabated. Have tried everything I can think of.
Basically do not understand why, when updated from build 18G103 to 18G3020, it won't run properly on the internal. (Never had this problem with Late '09 iMac).
All drives are HDD.
Any help, even wild guesses greatly appreciated.
I have Macmini 2010, but I have updated it to Catalina 10.15.3 and works fine with macOS Catalina Patcher on external HDD APFS. I use internal HDD only for backup, it is 10 years old and I fear it could be broken anytime after all the heavy work it has suffered.