HTTP Error 500.21 - Internal Server Error - Simple Solution
HTTP Error 500.21 - Internal Server Error Handler "PageHandlerFactory-Integrated" has a bad module "ManagedPipelineHandler" in its module list. If you getting above error after publishing your asp.net application in IIS 7 then following is the simplest solution for you. Go to command prompt. Navigate to C:\Windows\Microsoft.NET\Framework\v4.0.30319 path. Then type aspnet_regiis.exe -i and hit enter. If you got message like "Asp.net installed suuccessfully" then you have done it then. Remember you must have administrator rights to do the above procedure .