Where are really the log files to debug when a Windows 10 update fails?

I am struggling with a Win 10 update, in particular:

Feature update to Windows 10, version 1809 x64 2020-03B - Error 0x80070490

Google is swamped with useless articles about random experiences of people but no actual or systematic solutions. The usual solutions (DSIM, sfc) I did already.

According to my research, code 0x80070490 relates to a driver problem. But in device manager everything is OK, all my devices work as expected. Windows must somewhere place more information than this stupid code.

Supposedly there should be log files in c:\$WINDOWS.~BT\Sources\Rollback but "Rollback" does not even exist. Similarly, no (current) files in c:\Windows\Panther. No useful info in the Event log.

So, where does the update actually put the log files?

So, where does the update actually put the log files?

If an update fails to install the reason for the failure will be contained within %systemroot%\Logs\CBS. If Windows Update itself has an error, it will be logged within Event Tracing for Windows (.etl) files. If you run the PowerShell command, Get-WindowsUpdateLog, a human-readable text file will be generated.

Source: Windows Update log files

Supposedly there should be log files in c:\$WINDOWS.~BT\Sources\Rollback but "Rollback" does not even exist. Similarly, no (current) files in c:\Windows\Panther. No useful info in the Event log.

Based on my experience this log only applies to problems upgrading to another version of Windows.