Once in a time when you are browsing to your website and found that it is you site was showing "500 Internal Server Error" no need to panic just yet you may refer below information which may be helpful to you.
500 Internal Server Error Help (Linux/cPanel):
A 500 Internal Server Error can be caused by many things, including but not limited to invalid permissions, invalid ownership, bad lines in your php.ini or .htaccess file, invalid requests in the script, and others not mentioned here. Typically this is not a problem with the server itself, and can be most often resolved by modifying something in your site's configuration.
Please check the Error Logs in cPanel for specific information.
Example of Server 500 Error
A Server 500 error will generally look something like this:
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request. Please contact the server administrator, firstname.lastname@example.org and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Additionally, a 500 Internal Server Error error was encountered while trying to use an Error Document to handle the request.
Below are some possibilities of the Internal Server Error:
1) Bad permissions, Writable by group
A bad permissions error may look something like this:
Oct 04 12:03:22 2013] [error] [client 188.8.131.52] SoftException in
Application.cpp:601: Directory "/home/exampleuser/public_html" is
writeable by group. In this instance the folder had permissions for a
folder set too high. To correct this, the permissions need to be changed
from "777" to "755".
Directories and folders should be 755. Executable scripts within the cgi-bin folder must be 755. Images, media, and text files like HTML should be 644.
Files - 644
CGI Scripts - 755
Directories - 755
You can modify permissions with the File Manager, located in the "Files" category of the cPanel, an FTP client, or using the chmod command in SSH/Bash (Jailed Shell).
2) Bad .htaccess, Invalid code, command, or syntax
In the .htaccess file ("dot htaccess"), you may have added lines that are either worded badly or conflicting. The best way to troubleshoot this is comment out the lines in the .htaccess.
You can comment out a line in the .htaccess by adding # to the beginning. You are wise to save an original copy of any file before you make changes.
For example, if the .htaccess looks like this:
AddType application/x-httpd-php5 php
Then try something like this:
#AddType application/x-httpd-php5 php
Broken lines and lines that start with php_flag are the most common mistakes. If you cannot determine which line is the problem, then comment out every line.
3) Other common .htaccess errors:
An error may look like the following:
Oct 04 12:07:10 2013] [alert] [client 184.108.40.206]
/home1/examplec/public_html/.htaccess: Option FollowSymlinks not allowed
In this example the error is simple to fix; in the file
specified, use a permitted directive--in this case use
"SymlinksIfOwnerMatch" instead of "FollowSymlinks", or remove the line
Please refer below link for more details:
4) Syntax Not Closed:
An error may look like the following:
Oct 04 12:11:38 2013] [alert] [client 220.127.116.11]
<IfModule>ExampleRule/Module> was not closed.
Again, the solution is to simply fix the syntax, or remove it. In this case, close the ending "</IfModule>"; directive properly and put the rules on their own line to resolve the problem.
These are just a few common examples that can be caused by bad .htaccess parameters. What you encounter will likely vary, however generally the error message is
descriptive enough to determine an error from it without further investigation.
5) Still having issues?
If you are still having difficulties resolving this issue, our server administrators will be able to advise you how to avoid this error. Please come into live
support chat, call us, or create a support ticket. Please be ready to provide us with the steps needed to see the 500 error on your site.