Handler "ExtensionlessUrlHandler-Integrated-4.0" has a bad module "ManagedPipelineHandler" in its module list

Try to re-register ASP.NET with aspnet_regiis -i. It worked for me.

A likely path for .NET 4 (from elevated command prompt):

c:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i

http://forums.iis.net/p/1190643/2026401.aspx

If you're running into this error with Windows 8/Windows Server 2012 and .Net 4.5 follow these instructions here: http://www.britishdeveloper.co.uk/2013/01/handler-extensionlessurlhandler.html

Go to "turn Windows features on or off" Then Internet Information Services Then World Wide Web Services Then Application Development Features And then enable ASP.NET 4.5

This worked for me (although the wizard and wording is a little different in Windows Server 2012, but you'll figure it out). With this being said, why this is necessary after installing everything through the Web Platform Installer including all of the dependencies is completely beyond me...

Despite following most of the advice on this page, I was still getting problems on Windows Server 2012. Installing .NET Extensibility 4.5 solved it for me:

Add Roles and Features > Server Roles > Web Server (IIS) > Web Server > Application Development > .NET Extensibility 4.5

For Windows 10 / Windows Server 2016 use the following command:

dism /online /enable-feature /featurename:IIS-ASPNET45 /all

The suggested answers with aspnet_regiis doesn't work on Windows 10 (Creators Update and later) or Windows Server 2016:

C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i Microsoft (R) ASP.NET RegIIS version 4.0.30319.0 Administration utility to install and uninstall ASP.NET on the local machine. Copyright (C) Microsoft Corporation. All rights reserved. Start installing ASP.NET (4.0.30319.0). This option is not supported on this version of the operating system. Administrators should instead install/uninstall ASP.NET 4.5 with IIS8 using the "Turn Windows Features On/Off" dialog, the Server Manager management tool, or the dism.exe command line tool. For more details please see http://go.microsoft.com/fwlink/?LinkID=216771. Finished installing ASP.NET (4.0.30319.0).

Interestingly, the "Turn Windows Features On/Off" dialog didn't allow me to untick .NET nor ASP.NET 4.6, and only the above DISM command worked. Not sure whether the featurename is correct, but it worked for me.

Run one of these commands :

For 32 Bit Windows OS:

c:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i

For 64 Bit Windows OS:

c:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -I

This https://stackoverflow.com/a/13266763/1277458 works perfectly. But if you have 64-bit operation system use Framework64 instead of Framework in path:

c:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -i

The problem

You are using SimpleWorkerRequest in a scenario that it wasn't designed for. You are using it inside of IIS. If you look at the prior MSDN link (emphasis is mine):

Provides a simple implementation of the HttpWorkerRequest abstract class that can be used to host ASP.NET applications outside an Internet Information Services (IIS) application. You can employ SimpleWorkerRequest directly or extend it.

Also, if you look at the MSDN documentation for the System.Web.Hosting namespace (SimpleWorkerRequest is in this namespace), you will also see something similar to the above (again, emphasis is mine):

The System.Web.Hosting namespace provides the functionality for hosting ASP.NET applications from managed applications outside Microsoft Internet Information Services (IIS).

The solution

I would recommend removing the call to SimpleWorkerRequest. Instead, you can use a Microsoft solution to make sure your web site automatically starts up after it recycles. What you need is the Microsoft Application Initialization Module for IIS 7.5. It is not complicated to configure, but you need to understand the exact options. This is why I would also recommend the Application Initialization UI for IIS 7.5. The UI is written by an MSDN blogger.

So what exactly does the Microsoft solution do? It does what you are trying to do - IIS sends a "get" request to your website after the application pool is started.

In my case (Windows 10 + IIS 10) i had to open "Turn Windows Features On or Off" and then go to Internet Information Services > World Wide Web Services > Application Development Features > and check ASP.NET 4.6

I solved this problem, adding in "Turn Windows features on or off" The option ASP.NET 4.7

https://i.stack.imgur.com/UkPYT.png

Making this its own post because this had me going for hours.

I saw maybe a dozen of similar posts here and elsewhere about this problema and the aspnet_regiis fix. They weren't working for me, and aspnet_regiis was acting odd, just listing options etc.

As user ryan-anderson above indicated, you cannot enter .exe

For those less comfy with things outside IIS on the server, here's what you do in simple steps.

Find aspnet_regiis in a folder similar to this path. c:\Windows\Microsoft.NET\Framework\v4.0.30319\ Right-click command prompt in the start menu or wherever and tell it to run as administrator. Using the windows "Run" feature just won't work, or didn't for me. Go back to the aspnet_regiis executable. Click-drag it right into the command prompt or copy-paste the address into the command prompt. Remove, if it's there, the .exe at the end. This is key. Add the -i (space minus eye) at the end. Enter.

If you did this correctly, you will see that it starts to install asp.net, and then tells you it succeeded.

Make sure that you have set your application-site version from v2.0 to v4.0 in IIS Manager:

Application Pools > Your Application > Advanced Settings > .NET Framework Version

After that, install your ASP.NET.

For 32-Bit OS (Windows):

C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i

For 64-Bit OS (Windows):

C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -i

Restart your application-site in IIS Manager and enjoy.

I know this is an oldie, but thought I might add some value. For those of us running Server Core outside of a domain (domain members can just run Server Manager remotely to add/remove features/roles), you have to resort to command lines.

Powershell users can type "Install-WindowsFeature Web-Asp-Net45"

That should be equivalent to using server manager.

I was challenged by the same error message, with .net 4.7 installed.

The solution was to follow one earlier mentioned post to go with the "Turn Windows feature on or off", where the ".NET Framework 4.7 Advanced Services" --> "ASP.NET 4.7" already was checked.

Further down the list, there is the "Internet Information Services" and subnote "Application Development Features" --> "ASP.NET 4.7", that also needs to be checked.

When enabling this, allot of other features are enabled... I simply pressed the Ok button, and the issue was resolved. Screendump of the windows features dialog

I'm working on Windows Server 2012. .NET Extensibility 4.5 feature is on. WebDAVModule removed. I was still getting 500.21 error on ASP.NET route '/docs'.

Changing 'skipManagedModules' to false fixed the problem.

<applicationInitialization doAppInitAfterRestart="true" skipManagedModules="false">
        <add initializationPage="/docs" />    
</applicationInitialization>

Thanks to https://groups.google.com/forum/#!topic/bonobo-git-server/GbdMXdDO4tI

https://i.stack.imgur.com/4YJjP.png

I had this problem and found that removing the following folder helped, even with the non-Express edition.Express:

C:\Users\<user>\Documents\IISExpress

This error started happening to me out of nowhere last week, affecting the existing web sites on my machine. I had no luck with it trying any of the suggestions here. Eventually I removed WebDAV from IIS completely (Windows Features -> Internet Information Services -> World Wide Web Services -> Common HTTP Features -> WebDAV Publishing). I did an IIS reset after this for good measure, and my error was finally resolved.

I can only guess that a Windows update started the issue, but I can't be sure.

You could fix it by change the "ExtensionlessUrlHandler-Integrated-4.0" type in iis to System.Web.DefaultHttpHandler

For me, removing WebDAV from my server caused the application to return a 503 Service Unavailable Error message when using PUT or DELETE, so I re-installed it back again. I also tried completely removing .NET Framework 4.5 and reinstalling it and also tried re-registering as suggested but to no avail.

I was able to fix this by disabling WebDAV for the individual application pool, this stopped the 'bad module' error when using PUT or DELETE.

Disable WebDAV for Individual App Pool:

Click the affected application pool Find WebDAV Authoring Tools in the list Click to open it Click Disable WebDAV in the top right.

Ta daaaa!

I still left the remove items in my web.config file.

 <system.webServer>
    <modules>
      <remove name="WebDAVModule"/>
    </modules>
    <handlers>
      <remove name="WebDAV" />
    </handlers>
 <system.webServer>

This link is where I found the instructions but it's not very clear.

This maybe not a usefull solution for OP but it concerns the same "error" message.

We are hosting PHP pages on IIS8.5 with .NET 4.5 installed correctly.

We make use of the preload functionality to make sure our application is always responsive across the board.

After a while we started getting this error at random.

In the web.config : I put skipManagedModules to true, -> don't do this!

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
<applicationInitialization skipManagedModules="false" doAppInitAfterRestart="true">
  <add initializationPage="/" />
</applicationInitialization>
...

Although website is php, the routing to the paging is managed by the modules!!!

I also ran into that problem. My MVC4 App is running on a Windows Server 2012 R2 with IIS 8.5. None of these posted solutions worked for me...installing the missing frameworks through IIS Features could have solved it but the installation always failed.

I had to use the Web Platform Installer and installed the following packages:

https://i.stack.imgur.com/3hAi4.png

I was facing this issue in a web application hosted on a shared hosting server. So obviously did not have direct access to IIS, so could not apply many solution proposed here.

On the hosting provider's control panel I enabled error logging for IIS and ASP.Net. And then got to know that error actually lied in a missing cshtml.