Today Avast UI asked me to reboot in order to apply an update. After rebooting it no longer worked.
I already tried rebooting and repairing multiple times. I also uninstalled Comodo Firewall to rule out a conflict.
On startup the Avast tray icon appears normally, but left or right click doesn't do anything. After a while an Avast shortcut appears on the desktop and the tray icon becomes "crossed". The tooltip says "you are unprotected". Clicking to "update engine and virus definitions" returns "error 0x80046402". The Avast UI window says "Loading... This shouldn't take long". Windows Defender auto activated itself and does not mention anything about Avast being enabled.
According to C:\ProgramData\AVAST Software\Avast\report\FileSystemShield.txt the shields are not running.
I noticed various dumps in C:\ProgramData\AVAST Software\Avast\log.
The Avast services appear to be running, but "aswbIDSAgent" does not.
There are many errors in C:\ProgramData\AVAST Software\Avast\log\Amsi.log, like the following:
[2020-03-10 18:06:34.695] [error ] [AMSI ] [ 3224: 7048] AavmRpcAmsiScan 0x80046400
[2020-03-10 18:06:34.709] [error ] [AMSI ] [ 3224: 4236] AavmRpcAmsiScan in ScanBufferAndDelete(behavioral) 0x80046400
I also found the following in C:\ProgramData\AVAST Software\Avast\log\AvastSvc.log:
[2020-03-10 18:03:11.535] [error ] [aavm ] [ 3444: 3652] - avworkInitialize [13] (VPS: 20031000)
[2020-03-10 17:56:59.367] [fatal ] [aavm ] [ 3448: 3652] AavmStart failed, error 0x8007000D!
Exception: Could not create engine handle
Code: 0x8007000d (-2147024883)
C:\ProgramData\AVAST Software\Persistent Data\Avast\Logs\Update.txt contained the following:
[2020-03-10 18:04:33.293] [notice ] [conn ] [10988: 6764] Create: waiting for the service to be ready (max. 30sec)
[2020-03-10 18:05:03.293] [warning] [instcore ] [10988:10284] AvastConnector::GetIpmParameters call has failed with code 2147771392
[2020-03-10 18:05:03.293] [error ] [shepsync ] [10988: 6764] url params callback failed (0x80046400)