After starting from cli I get:
javaldx: Could not find a Java Runtime Environment!
Warning: failed to read path from javaldx
which leads to a file named '/home/michael/.config/libreoffice/4/user/config/javasettings_Linux_X86_64.xml', which originally held links to the formerly installed version 8 of the JRE. The internet recommended to delete it, and afterwards a new one was auto-generated, but with no link to a Java runtime environment at all. I even tried to manually edit this file but with no success.