Programming Answer: 500 Internal Server Error when adding a line in the .htaccess file

I need to add the following line into my .htaccess file in order to get my website working with mod_security

SecFilterScanPOST Off

but then I get an error

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

In my WebHost manager I see the following message: mod_security is installed and running!

I do not know what I did wrong?

From serverfault Roland

Check your apache error log (on linux it is usually in /var/log/http/error_log or similar).

From $pageUsers[$post.author].name
That module is probably not loaded. Try it within a <IfModule> block to avoid such error:
```
<IfModule mod_security.c>
    SecFilterScanPOST Off
</IfModule>
```
But note that this doesn’t solve your problem. It just avoids that internal error.

To solve your problem, make sure that the mod_security module is loaded. This is done with the LoadModule directive.

Roland : In my WebHost manager I see the following message: mod_security is installed and running!

Gumbo : @Roland: Then your mod_security module is probably not intended to be used in a .htaccess file. Maybe it’s just allowed in the server/virtual host configuration.

From Gumbo
You can check if the SecFilterScanPOST directive is allowed in .htaccess files (probably via an AllowOverride option in your Apache or VirtualHost config file).

From juba
If your mod_security version is 2 or greater you can't put directives in a .htaccess file - only httpd.conf will do. I suppose they'll add this to the FAQ sooner or later.

From djn

Programming Answer