Hi all,
got the ERROR 500 message after the upgrade of my dokuwiki website.
Here is how I fixed it.
I downloaded the new version of Dokuwiki https://download.dokuwiki.org/ (choose your main language and choose the usual plugins that are suggested on the page)
I used FileZilla to connect to my website via FTP protocol. I renamed /lib/plugins to /lib/plugins-backup.
From the new Dokuwiki I just downloaded, I got the /lib/plugins folder and uploaded it to my website via FTP.
The website works ok, but without all the plugins I added, so I had to add them again, one by one, via the admin page (http://youwebsite.com/doku.php/index?do=admin)
While installing the plugins one by one, I stumbled upon one that broke the system again (ERROR 500): in my case it's the plugin pglist (https://www.dokuwiki.org/plugin:pglist)
I could reinstall all my other plugins and my website is working ok now. Check this forum, other users have identified problematic plugins with HogFather.
Keep the good vibes alive!
Greg from France
http://www.gregorygutierez.com