Not Found:404 with coldfusion.ajax.submitform on IIS7

A friend ran into this error when migrated a CF8 application to IIS7:  

Not Found:404 

It happens when executing a coldfusion.ajax.submitform of a form with quite many fields and values....

As you know, coldfusion.ajax.submitform sends a request to the handler page via URL, that contains the whole structure of the referenced form with it's selected values.   In some cases this means the resulting URL can be very large depending on the complexity of the referenced form.

IIS7 apparently has a lower tolerance to URL Requests size limits than IIS6 had... and in order for some ajax.submitform to work, you would need to increase the size limits on your IIS7.  This is done on REQUEST FILTERING like this:

The red out values have to be increased to match the length of your form.. so it allows IIS7 to send it as an URL Request ...