My site is a subdomain.
When I load a file from a folder, which is in the root folder, it displays an internal server error in firebug.
Why does my subdomain displays internal server errors?
This is the php code:
require_once 'xxx/test.php';
xxx is a directory in the root folder and I am trying to load the test.php page. That's where I got the internal server error.
check the logs, most the time located at /var/log/apache/php.errors you can use tail -f in conjunction to monitor the log file while you refresh the page...
tail-f /var/log/apache/php.errors
Check File permissions, temporarily apply chmod -R 777 to httpdocs (or whatever your http root is).
Check PHP Code A lot of times "internal Server Error" is caused by an error 500 which is generated when PHP code has a critical syntax error. Delete the require file, or try requiring another file with something simple such as <?php echo 'hello world'; ?> in it. If the error goes away then its most likely within that required file, check your syntax.. If you still can't figure it out.. post it up here.
.htAccess error Another cause can be problems with your .htaccess file, rename/delete it or comment all the lines out within. See if the error goes away, if it does check your syntax.