I'm struggling with the Update from Stretch to Buster to support my R-Pi 4B.
I did the update using a R-Pi 3B (not a +)
I used Win32DiskManager to backup the configuration as I went along.
I was using a scratch 16GB SD card for the update.
I went through the update yesterday (took a LONG time, like8+ hours, extremely slow download of wolfram-engine).
The last lines of the update showed failures, so I had to re-run the update. (I did save the terminal output, but it's on the Buster config file save in the Win32DiskManager file.)
Once I got into that, there was some configuration questions about Mumble, so I answered "yes" to letting it use the installer's configuration.
Once I got through the second round, and the reboots, things looked OK, except that Mumble won't connect.
I went back to the original configuration (Stretch) looking for a way to save the Mumble configuration, to be able to use it in the Buster version, but there is no save.
Can I just use the /etc/mumble.server.ini and mumble.server.ini.dpkg-dist files (copy and put in the Buster config)?
I'm tempted to re-try the update.
I have this feeling that this may just be the first of the problems that I need to resolve...
I did check and the update does run on my R-Pi 4B.