If your application is using ASP.NET 4 ensure that this is registered in IIS. The following command should register it using the aspnet_regiis.exe tool: c:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis -
ir (adapt the paths with the proper version of the framework if necessary).
Ensure that the application pool which is configured for the website is using Integrated pipeline mode.