There are a few common causes for this error code including
problems with the individual script that may be executed upon
request. Some of these are easier to spot and correct than
others.

File and Directory Ownership

The server you are on runs applications in a very specific way
in most cases. The server generally expects files and
directories be owned by your specific user cPanel
user. If you have made changes to the file ownership
on your own through SSH please reset the Owner and Group
appropriately.

File and Directory Permissions

The server you are on runs applications in a very specific way
in most cases. The server generally expects files such as HTML,
Images, and other media to have a permission mode of
644. The server also expects the permission
mode on directories to be set to 755 in most
cases.

(See the Section on Understanding Filesystem
Permissions.)

Command Syntax Errors in .htaccess file

In the .htaccess file, you may have added lines that are
conflicting with each other or that are not allowed.

If you would like to check a specific rule in your .htaccess
file you can comment that specific line in the .htaccess by
adding # to the beginning of the line. You should always make a
backup of this file before you start making changes.

For example, if the .htaccess looks like

DirectoryIndex default.html
AddType application/x-httpd-php5 php

Then try something like this

DirectoryIndex default.html
#AddType application/x-httpd-php5 php

Note: Due to the way in which the server
environments are setup you may not use
php_value arguments in a .htaccess file.

Exceeded Process Limits

It is possible that this error is caused by having too many
processes in the server queue for your individual account.
Every account on our server may only have 25 simultaneous
processes active at any point in time whether they are related
to your site or other processes owned by your user such as
mail.

ps faux

Or type this to view a specific user’s account (be sure to
replace username with the actual username):

ps faux |grep username

Once you have the process ID (“pid”), type this to kill the
specific process (be sure to replace pid with the
actual process ID):

kill pid

Your web host will be able to advise you on how to avoid this
error if it is caused by process limitations. Please contact
your web host. Be sure to include the steps needed to see the
500 error on your site.