Continuing, the downgrade to the release version appears to have worked. I restored an older 4.3 back up and it seems to be running.
Confirmed java version in advance of trying OH5M3 again:
openhabian@oh-m5:~ $ java -version
openjdk version "21.0.7" 2025-04-15 LTS
OpenJDK Runtime Environment Temurin-21.0.7+6 (build 21.0.7+6-LTS)
OpenJDK 64-Bit Server VM Temurin-21.0.7+6 (build 21.0.7+6-LTS, mixed mode, sharing)
openhabian@oh-m5:~ $
The openhabian change to OH5M3 appears to have worked. I’ve got a couple of months of changes and improvements to redo, but at least it is working.
I wonder if I could load the snapshot version I was running when I had a more recent backup and update it to M3.
It looks like it should be possible if I knew where to look. This is old, but supports the idea:
I followed the steps here,
but it looks like only recent snapshots are shown:
openhabian@oh-m5:~ $ apt list -a openhab
Listing... Done
openhab/unstable,unstable 5.0.0~S4725-1 all [upgradable from: 5.0.0~M3-1]
openhab/unstable,unstable 5.0.0~S4723-1 all
openhab/unstable,unstable 5.0.0~S4722-1 all
openhab/unstable,unstable 5.0.0~S4721-1 all
openhab/unstable,unstable 5.0.0~S4720-1 all
openhab/unstable,unstable 5.0.0~S4718-1 all
openhab/unstable,unstable 5.0.0~S4717-1 all
openhab/unstable,unstable 5.0.0~S4716-1 all
openhab/now 5.0.0~M3-1 all [installed,upgradable to: 5.0.0~S4725-1]