Keychain problem after crash?
Since updating my 2017 MacBook Pro (16 GB RAM, 2.5 GHz dual-core i7) for the supplemental update to OS X 10.15.4, it has been very unstable, crashing continually, sometimes on start up.
I tried using DiskUtility to do first-aid on the (SSD) hard drive in recovery mode, but that failed. Still, finally it was able to complete a full Time Machine backup last night, and today the computer had a good day: no crashes, fan quiet, peppy, no error messages. So I thought I would risk opening Ableton. This crashed it again.
Now whenever I log in, I get a white screen and an alert saying the computer crashed and do I want to reopen windows, though I shut the computer down myself. The next thing that happens is I get the following messages:
Unrecoverable error. Security Agent was unable to create requested mechanism loginKC.queryCreate
sharingd wants access to the keychain (this goes away when I put in the admin password)
callserviced wants to use keychain (this also accepts the admin password)
I also get an alert saying the Mac cannot connect to iCloud because of a problem with my username. But if I sign in again through the Apple ID preferences pane, I get "an unknown error occurred."
Keychain Access shows empty keychains for login, system, and System Roots. The iCloud passwords are there.
I believe this might have something to do with why I can no longer open any Apple software: Safari, Mail, Stickies, Music, Notes, etc --- all crash immediately after I try to open them. Utilities like Activity Monitor and Keychain Access work. And most third-party software seems to work (I'm not trying to open Ableton again, but I'm writing this on Firefox, for example, and that is fine). The LastPass app crashes like an Apple app. Interestingly (maybe), the Signal desktop app, still works.
Any ideas what might be going on? Any ideas how to fix it?
I didn't experience problems with 10.15.4 until the supplemental update.
I would be very grateful for any help fixing this.
MacBook Pro 13", macOS 10.15