500 Internal Server Error

PPJ

Hi everyone i just installed and everything went fine; after installation had finished i went to the admin panel, change the logo and site description then went back to the main page, but instead of showing the main page it shows 500 Internal Server Error.

This is my error_log from PHP
[23-Dec-2016 17:24:53 America/New_York] PHP Fatal error: Class 'Flarum\Forum\Server' not found in (DELETED MY PATH)/forum/index.php on line 14

What could be the issue?

ram0ng1

PPJ | thunder
I tried installing on WAMPSERVER 64 BITS (X64) 3.0.6 with Apache 2.4.23, PHP 5.6.25, MySQL 5.7.14, PhpMyAdmin 4.6.4, Adminer 4.2.5 and PhpSysInfo 3.2.5 even though it gave Error 500:
500 internal server error

*I would like to know how to solve

thunder

Can you list what you are using?
What PHP version, is it apache, etc.
Will probably speed up the help.