iMac Catalina Console errors?

Seeking guidance from the community…

Background: I updated to Catalina 10.15 a couple weeks ago. Since then my iMac is exhibiting strange behavior at times.

Model: Late 2012 iMac
Boots and runs from USB3-connected external drive


  • I sometimes come back to find a ‘Disk Utility’ window on the screen – the one with the four or five options only
  • Right now my fans are running. Not sure if this is because I just reset SMC and PRAM, or if it is because of the strange and copious Console messages (see below).