At one time or another every WordPress web developer has experienced the WordPress Internal Server Error. When it happens it can be scary. In this post I will go through the most common reasons why the WordPress Internal Server Error occurs.
A few things to try
Check your .htaccess file
Rename your .htaccess to .htaccess-old and try to re-connect to the site in question. If that fixed it, log into your WordPress site, go to settings / permalinks and click save. That will re-write your .htaccess file.
Check your WordPress memory limits
Create a php.ini file and add this line to it ---> memory=64mb. Upload it to the wp-admin folder. If this corrects the issue, you will need to figure out which plugin is causing the memory limits to be reached. You may need to contact your web host for assistance.
Check your plugins
You can deactivate all your plugins at once by renaming your plugins folder to something else. If you are able to access your website after doing this, then one of your plugins is the issue.
Check your wp-admin and wp-includes directories
Download a fresh copy of WordPress and upload the wp-admin and wp-includes folders in place of the one's on your server.
Check your file permissions
These setting are default and will work.
644 -rw-r--r-- /home/user/wp-config.php
644 -rw-r--r-- /home/user/cgi-bin/.htaccess
644 -rw-r--r-- /home/user/cgi-bin/php.ini
755 -rwxr-xr-x /home/user/cgi-bin/php.cgi
755 -rwxr-xr-x /home/user/cgi-bin/php5.cgi
My web host recommends 644. 644 is usually the default for most web hosts.
When all else fails contact your web host for assistance with this issue or hire a guy like me. I can be reached from my contact page or 954-895-2555.