I’ve recently encountered the following error in my IIS after starting a (previously) working ASP .NET application:
Handler “ExtensionlessUrlHandler-Integrated-4.0” has a bad module “ManagedPipelineHandler” in its module list
(or in German: Der Handler “ExtensionlessUrlHandler-Integrated-4.0” weist das ungültige Modul “ManagedPipelineHandler” in der Modulliste auf)
The error appeared after a fresh reinstall of Windows. After a lot of googling around for the problem I realized that the installation order of IIS and .NET framework leads to this error (WTF Microsoft).
The solution is to simply re-register ASP .NET in IIS.