iFinity

OK that makes sense why the DNN page is getting loaded, because the 404 page inherits from the PageBase object, which tries to determine the page culture based on the currently loaded portal settings. 

Try this:

change the 'ignoreRegex' field to this value:

(?<!linkclick|404\.aspx.+)(?:\.pdf$|\.gif$|\.png($|\?)|\.css$|\.js($|\?)|\.jpg$|\.html$|\.htm$|\.axd($|\?)|\.swf$|\.flv$|\.ico$|\.xml($|\?))

and change the 'doNotRewrite' field to this value:

/DesktopModules/|/Providers/|/LinkClick\.aspx|404\.aspx

Apply the changes and let me know if that works.

The theory is to allow the 404.aspx call to be processed by the Url master module to the pont of establishing which portal the request is for, but not to be rewritten.

Ok, thanks for letting me know.  I'll start writing a compatiblity page for the Active Social module.  As an aside, I'm working on the User Profile feature to make it compatible with Active Social so you don't have to implement the 404 handler.  I'll see how I go with that.