Since last week, many of my websites were plagued by the infamous “500 – Internal Server Error”. The web hosting company did have problems regarding this particular type of error on many of their hosted websites and I decided to simply wait and see. Today, I realized that only my WordPress subdirectories remained affected by the 500 error; all of the other subdirectories (not based on WordPress) were doing just fine.
After verifying a few things, I found out that the main problem may have been caused by a plugin which enabled the mobile-version theme of my WordPress website.
Hence, if you experience such 500 errors and if your website or part of it is based on WordPress, it may be a good idea for you to disable and/or uninstall such compatible mobile theme plugins. This solution is not perfect since I liked the plugin I used, which allowed my tablet and mobile phone users to see my website through a mobile-compatible theme but it was either that or not allowing any of my visitors to access my web pages!
If you still have problems with the 500 error after uninstalling such plugins, then it may be a good idea to contact your web hosting service…
Moreover: make sure to install All In One WP Security & Firewall and set it up properly (it will appear as WP Security in the dashboard). For Yahoo Web Hosting users, do not use the plugins W3 Total Cache and WP Super Cache since they require access to your .htaccess file and Yahoo Web Hosting does not include such a file (or any other file starting with a dot, which is weird but that’s how it is). If you have such a caching plugin in your WordPress, uninstall it and install this plugin instead: Hyper Cache.