Dear Camille,
thanks a lot for the prompt reply!
We are at WP 5.5.3 localized to Czech. All plugins are usually also on the latest version, so this shouldn’t be an issue. A was rather thinking about some corner case configuration carried through decade.
I was also suspecting plugin ‘Event Calendar 3 for PHP 5.3’, as this is a quite old and unsupported plugin. But I cannot easily disable it. My friend is currently fixing it.
Anyway, I don’t know the root cause of our crash, although the workaround is fixing the segfaults. I’m not a big fan of adding some check which may hide a bug which will arise later. So I will dig deeper and let you know.
Thanks again,
Tomas