I changed something in the Admin settings (Admin Area -> Utilities -> Admin settings).
This seems to recreate the config.php in root.
When I tried to edit a member after wards, I received this error
Strangs. So I looked for it. Finally I noticed, that in config.php (fortunately there is a config.bak.php).Not Found
The requested URL /admin/admin/pageEditMember.php was not found on this server.
So in this config.php in line 6 $appURI is now defined: My editing (and I did not change any setting that could have forced changes to this variable) was suddenly 'admin' instead of '' (nothing). I removed the admin and set nothing again - and it works.
Maybe someone else should check on that to confirm.
Left: New, right: old (I messed up the extensions I noticed) Olaf