I use a portable flavor of Calibre (through batch script and environment variable).
What I do is install Calibre normally, then zip folder and uninstall. Then extract zip in my USB drive and run it through script to pick both library and config from the USB disk.
The idea was to install latest beta and copy content over the current build on my USB disk.
However, I did it but calibre did not start.
Then I copied over previous build again but db seem to have been upgraded so did not work properly neither.
Fortunately I had a metadata backup
