I tried to delete the archiveupload folder as suggested.
Then the next error message popped up regarding doodle plugin, which I also deleted.
Both plugins were rarely used.
But now the following message pops up:
Fatal error: Declaration of syntax_plugin_gcalendar::handle() must be compatible with dokuwiki\Extension\SyntaxPlugin::handle($match, $state, $pos, Doku_Handler $handler) in /home/httpd/vhosts/bockler.ch/subdomains/wiki/httpdocs/htdocs/lib/plugins/gcalendar/syntax.php on line 0
This is critical now, because the calendar is used intensivally and many dates are in the calendar.
It seems it is not only to archiveupload plugin but a larger issue. Who can help me?
If I have to delete all plugins, I have to start from the very beginning and the sense of our wiki is obsolete. All data will be lost...
I really regret that I updated to Hogfather. But it was described as a stable version and not as a release candidate!
I am helpful for every hint and support.
Kind regards, Frank