500.21 Bad module "ManagedPipelineHandler" in its module list

Please follow these steps:

1) Run the command prompt as administrator.

2) Type either of the two lines below in the command prompt:

%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i

or

%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -i

I ran into this error on a fresh build of Windows Server 2012 R2. IIS and .NET 4.5 had been installed, but the ASP.NET Server Role (version 4.5 in my case) had not been added. Make sure that the version of ASP.NET you need has been added/installed like ASP.NET 4.5 is in this screenshot.

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

To fix the problem, I tried to run

%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -i

However It didn't work for me. I have to run another command line in CMD window as administrator. Here is the command:

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

or

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

Hope it will help.

Try switching to Integrated mode. See the following thread:

IIS 7, HttpHandler and HTTP Error 500.21

I got this error on my ASP.Net 4.5 app on Windows Server 2012 R2.

Go to start menu -> "Turn windows features on or off". A wizard popped up for me.

Click Next to Server Roles

I had to check these to get this to work, located under Web Server IIS->Web Server-> Application Development (these are based on Jeremy Cook's answer above):

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

Then click next to Features and make sure the following is checked:

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

Then click next and Install. At this point, the error went away for me. Good luck!

This is because IIS 7 uses http handlers from both <system.web><httpHandlers> and <system.webServer><handlers>. if you need CloudConnectHandler in your application, you should add <httpHandlers> section with this handler to the <system.web>:

<httpHandlers>
    <add verb="*" path="CloudConnect.aspx" type="CloudConnectHandler" />
</httpHandlers>

and also add preCondition attribute to the handler in <system.webServer>:

<handlers>
  <add name="CloudConnectHandler" verb="*" path="CloudConnect.aspx" type="CloudConnectHandler" preCondition="integratedMode" />
</handlers>

Hope it helps

I had this issue in Windows 10 when I needed IIS instead of IIS Express. New Web Project failed with OP's error. Fix was

Control Panel > Turn Windows Features on or off > Internet Information Services > World Wide Web Services > Application Development Features

tick ASP.NET 4.7 (in my case)

For me, I was getting this error message when using PUT or DELETE to WebAPI. I also tried re-registering .NET Framework as suggested but to no avail.

I was able to fix this by disabling WebDAV for my 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.

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

I had this problem every time I deployed a new website or updated an existing one using MSDeploy.

I was able to fix this by unloading the app domain using MSDeploy with the following syntax:

msdeploy.exe -verb:sync -source:recycleApp -dest:recycleApp="Default Web Site/myAppName",recycleMode=UnloadAppDomain

You can also stop, start, or recycle the application pool - more details here: http://technet.microsoft.com/en-us/library/ee522997%28v=ws.10%29.aspx

While Armaan's solution helped get me unstuck, it did not make the problem go away permanently.

if it is IIS 8 go to control panel, turn windows features on/off and enable Bad "Named pipe activation" then restart IIS. Hope the same works with IIS 7

I discovered that the order of adding roles and features is important. On a fresh system I activate the role "application server" and there check explicitly .net, web server support and finally process activation service Then automatically a dialogue comes up that the role "Web server" needs to be added also.

Install .NET framework as below, it will work .NET version 4.5 as well.

%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -ir

Some time only give aspnet_regiis.exe -i don't work so give aspnet_regiis.exe -ir in above path.