I was receiving a 500 internal server error on one of my CPanel sites earlier tonight but the apache error logs in CPanel admin for that user showed nothing. Instead, I had to locate the global apache error logs. This information may help others so I’ve listed some of the most useful CPanel/WHM log file locations below:
General Error and Auditing Logs:
Location : /usr/local/apache/logs/error_log
Description : All exceptions caught by httpd along with standard error output from CGI applications are logged here..
The first place you should look when httpd crashes or you incur errors when accessing website.
Domain Access Logs:
Location : /usr/local/apache/domlogs/domain.com
Description : General access log file for each domain configured with cPanel.
Apache Access Logs:
Location : /usr/local/apache/logs/access_log
Description : Complete web server access log records all requests processed by the server.
MySQL General Information and Errors:
Location : /var/lib/mysql/$(hostname).err
Description : This path could vary, but is generally located in /var/lib/mysql. Could also be located at /var/log/mysqld.log
For more log file locations, there are some great forum posts here and here.