Was asked to troubleshoot a client’s installation technique for WordPress on CentOS 6.x yesterday; they were receiving an Error 500 when they tried to access index.php for the first time. Checking the Apache logs showed:
SoftException in Application.cpp:431: Mismatch between target GID (522) and GID (65531) of file “/home/andrea/public_html/index.php”
Premature end of script headers: index.php
What was happening was that the client was un-tarballing the latest.tar.gz file as root and then changing the ownership of the file with the following:
chown -R [user] *
Changing that command to:
chown -R [user]:[usergroup] *
e.g. here:
chown -R andrea:andrea *
fixed that error. By not specifying the new group there was an ownership mismatch where the system expected one group but got another. There are many causes for an Error 500 – it’s a good habit to check the Apache logs first for pointers as to where to start troubleshooting.