Having troubles with url-rewriting using .htaccess on wamp server - apache

Question

I'm trying to rewrite the url of a certain php file.
Aim for url: www.mysite.com/filename/topic/ or www.mysite.com/filename/topic
What works: www.mysite.com/filename and www.mysite.com/topic
I've tried all rewrite rules I know which should work, but every time I add the topic to the url I end up with a 500 internal server error
Current .htacces file
<IfModule mod_rewrite.c>
Options +FollowSymLinks
RewriteEngine On
//No need for php extension
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteRule ^(.*)$ $1.php
//Rewriting the url
RewriteRule ^([a-zA-Z0-9_-]+)$ filename.php?topic=$1
RewriteRule ^([a-zA-Z0-9_-]+)/$ filename.php?topic=$1

Answer 1

You have conflicting rules and there is probably an issue with content negotiation with MultiViews. Also you aren't using all the flags ([L]) need to prevent continuation of rules matching.
You can't do it that way with the second set of rules and you don't need 2 rules just to have a / or not. You can make it optional. You need to do something like this.
<IfModule mod_rewrite.c>
Options +FollowSymLinks -MultiViews
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteRule ^([^/]+)/?$ $1.php [L]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^/]+)/([^/]+)/?$ $1.php?topic=$2 [L]
</IfModule>