Wordpress Error 500 has been widespread concern for most WordPress users. The only possible cause behind this category error directly or indirectly relates to the internal server. This error is not only specific to WordPress; however, it can be encountered with any website or server. In WordPress, error code 500 occurs either due to plugin or theme functions or corrupted .htaccess file. You can try following different ways to troubleshoot the error:
Check .htaccess file, rename it with some other name. After doing this, if your problem is solved, then no need to go for another option.
Increase the memory limit of PHP, in case you are not able to upload images or login to your admin account.
Deactivate all plugins if above given both solutions dont work for you. As it is hard to find a specific plugin responsible for this problem, deactivating all plugins at once is only the solution to find the right.