What is 500 Internal Server Error
It is probably the most notable WordPress error. After using your WordPress site for several consistent days, you wake up one day and find a message detailing that the server encountered an internal error. The renowned cause of this error is internal corruption of .htaccess files. Additionally, incorrect WordPress installation can also result in this error. The other possible cause of 500 internal server error is suspicious plugin or theme. It is also worth noting that at times limited PHP memory can also result to this error.
In order to fix this error, you will need to find out where the problem lies. One easier way of achieving that is by enabling automatic WB_DEBUG checking of error logs. In case the error turns out to corrupt .htaccess file, you will have to access FTP on your server. Get to the root directory of WordPress installation and find this file. Give the file a new name like .htaccess_used. Try reloading your website again after doing this. Most definitely it will work.
Another simple solution lies in deactivation of plugins and themes. Additionally, you can also try increasing the PHP memory because limited memory can also cause this error.