Internal Server Error when user wants to edit post

[Man_Utd_4Ever]

hi everybody
recently i started a forum.my cpanel is direct admin.
when users wants to edit their post and put more than 3 links this problem occur.

Forbidden

You don't have permission to access /editpost.php on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

i changed editpost.php permission but still problem

please help me to solve this problem

 

[SeLLeRoNe]

Is the owner of the file correct? Are you using mod_ruid2 or suphp for file owner security?

 

[zEitEr]

please help me to solve this problem

First of all you should start with reading apache's logs for the affected virtual host (domain).

Examine your .htaccess files located from the directory with editpost.php and upper.