The problem I am having is that I can not log on to my newly created wiki that I made using MediaWiki. I have searched the web for an answer, and the ones I found did not help w
If you are using NGINX + PHP-FPM the previous answers will likely not solve your problem.
From my experience, this issue is caused when php-fpm doesn't have write access to the cookie_path. You can find this path by running:
php-fpm -i|grep --color cookie_path
See what your cookie_path is, then stat the folder and ensure your php-fpm user has write access to it.
To resolve this issue using Nginx and Php-Fpm, I had to change my cookie_path from it's default of / (seriously, why would this be a default?) to /tmp.
After restarting nginx and php-fpm, it works perfectly.