Comment 14 for bug 1969949

I had the same problem today and tested many hours (many, many snapshot restores :D). Just in case, I can help with my solution: Although, I installed postgresql-plpython3-10 before updating, I got the mentioned errors. After some research, I found out, that I currently used Postgres 9.5 and the plpython3-package is only for Postgres 10 (actually the name of the package says it too). So, after migrating my DB to postgres 10, all went fine and I could update our landscape-server :)

small special hint: before updating postgres, I also needed to install the folllowing packages, so that the migration of the DB went fine:
postgresql-plpython-10
postgresql-9.5-debversion
postgresql-10-debversion