I have two Windows 2008 R2 Servers running an asp.net 4.0 app. The server that is having problems actually loads asp.net pages just fine, but if there are any ajax calls they don't work. I noticed there are no .net 4.0 specific Handler Mappings in IIS for this server like the other server has.

It's literally missing all .net 4.0 mappings (.axd, .soap, .cshtm, .ashx and even .aspx). I've tried running "aspnet_regiis -ir" but that didn't help. Should I reinstall the .net 4.0 framework? Manually add all these missing mappings? Is there something else going on?

What I don't want to do is add a ton of handlers to a web.config, they aren't needed on the server that works so it shouldn't be needed on the broken one.


3 Answers 3


Thanks for your answer but I have already checked the root handlers which are the same as the application handlers and missing all the .net 4 ones.

Problem solved. All I had to do was to execute aspnet_regiis in %WinDir%\Microsoft.NET\Framework64\v4.0.30319

In IIS 8, we have to go to "Turn Windows feature ON and OFF" and got to "Internet Information Services > World Wide Web Services > Application Development Features" and select "ASP.Net 3.5, ASP.Net 4.5 and ISAPI Extensions and Filters"


It turns out that the root Server Node in IIS had all the appropriate handlers, but for some reason the web site in question (i.e. Default Web Site) did not have the handlers. I simply clicked Revert to Inherited in the right nav of IIS in the Handler Mappings section and all is working well now.


Don't forget to add the "-i" parameter!

exe -i
Microsoft (R) ASP.NET RegIIS version 4.0.30319.17929
Administration utility to install and uninstall ASP.NET on the local machine.
Copyright (C) Microsoft Corporation.  All rights reserved.
Start installing ASP.NET (4.0.30319.17929).
Finished installing ASP.NET (4.0.30319.17929).


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