I have the same problem as well in my test environment. I currently have 3 Sitefinity projects running on there and all of a sudden I cannot access any editing. This is the error I receive from Fiddler.
I have both the SVC and XAMLX mappings you have mentioned.
Here's a PowerShell script I wrote to map the handlers for you:
# Set this to the web app path
"IIS:\Sites\Default Web Site\"
"Installing IIS Mapping Handlers."
$exists = Get-WebHandler -name
-PSPath $appNamePath -ErrorAction SilentlyContinue
( !$exists )
-Path *.svc -Verb
-PSPath $appNamePath -Type
"System.ServiceModel.Activation.ServiceHttpHandlerFactory, System.ServiceModel.Activation, Version=188.8.131.52, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
-Modules IsapiModule -PSPath $appNamePath -ScriptProcessor
-Path *.xamlx -Verb
"System.Xaml.Hosting.XamlHttpHandlerFactory, System.Xaml.Hosting, Version=184.108.40.206, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
Just in case it could help someone. I had this issue on one of my servers.
Make sure WCF is fully installed in "Windows programs and features. -> .NET 3.5 -> WCF".