Trouble with forum inside another Web application

When you have a site with its web.config file and installed the forum under the site root, sometimes you will run into weird problems running the forum. For example, the WYSIWYG (or Rich Text editor) will run into problems like

localization_en_US is not defined

MsgEditor is undefined

The reason for these weird errors is mostly due to web.config inheritance - the forum inherits the settings from your own web.config file which causes conflicts with its own settings.

Also, you may experience issue like registration failures and log in failures that present as "verification failure" or with WinXP the complete inability to enter a unique user name or password.

The solution: Break the inheritance

In your site web.config, add the following:

<location path="." inheritInChildApplications="false">      
    <system.web>      
    <!-- various settings -->
    </system.web>  
    <system.webServer>
     <!-- various settings -->
   </system.webServer>
 </location>

This should prevent inheritance from happening between the site and the forum.

If the issue happens on a different level than system.web e.g. if it shows an error like the following:
 
Section or group name system.web.extensions is already defined
 
You will need to follow the instruction Microsoft gives in this article as this is a bug or limitation of the .NET environment (see the second response):
 
http://connect.microsoft....ns-inheritance-problem