Server Error after upgrading from PHP4 to PHP5

[nanaimobar]

Downloaded latest version of vBulletin with the PHP5 extension, uploaded files to server in same location as prior files, update was successful but when I clicked on the admin login window a 500 server error appears. Prior files had php extension.

Any suggestions as to what I did wrong?

Thanks.

Moved to server forum section.

[Dismounted]

You don't need to use the .php5 extension. It's just there because some people have both PHP4 and PHP5 installed, using .php and .php5 to separate which files use which version.