Crash after moving or copying pages

Hello all,

we have problems with our xwiki system on debian.
our users have created some pages with images an charts without problem so far.
now they need the ability to move pages to build a solid strukture with subpages etc.

xwiki has a build-in option to move or copy pages but when we want to move or copy the whole website goes down.
after restarting the server, sometimes simple testing pages were in fact copied but not moved as requested. most of the time the move requests is not executet at all.
same error when we want to copy sites.
there is no process consuming lots of cpu, the site is just unreachable after a few seconds.
restarting tomcat alone doesn’t solve the problem, since now I’m restarting the whole system.

i must submit, i don’t know where to begin to find errors since all other funktions work as expected and I’m new to xwiki.

here are some more details:
Debian 10, 4GB ram, 2vcpu, Vmware
Clients use Chrome and Firefox with nearly the latest versions

we also did update to xwiki version 12.4, the error is still there

which logs can I supply for further investigation?

thank you for your help in advance.