Forbidden and Not acceptable errors?

[Zachery]

My users and myself are having issues with blank pages, forbidden and not acceptable errors, what can I do?

There is a very good chance your host has installed a add-on for apache called mod_security.

ModSecurityTM is an open source intrusion detection and prevention engine for web applications (or a web application firewall). Operating as an Apache Web server module or standalone, the purpose of ModSecurity is to increase web application security, protecting web applications from known and unknown attacks.

While mod_security can be a very powerful tool, misconfigured or overly strict rule sets can interfere with vBulletins Operation. Below for Apache users you can use an htaccess file and add a specific rule to disable mod_security.

Make or edit your forum .htaccess file and add the following code

<IfModule mod_security.c>
   SecFilterEngine Off
   SecFilterScanPOST Off
</IfModule>

Note, place this file in your main forum directory.