'.ashx' has not been pre-compiled, and cannot be requested.
Afer a little investigation we came up with 2 solutions:
- First solution - not recommended: App Pools - Managed Pipeline Mode changed it from Integrated to Classic Not recommended because you are basically giving up an all good IIS7 functionality - the common event pipeline. (More info)
- Second solution - recommended: Move/copy the content of
system.web - httpHandlers to
system.webServer - handlers
In this case you'll might need to consider several other attributes for a handler (More info)