BizTalk-There was a failure executing the receive pipeline - Attempted to access an unloaded AppDomain

BizTalk-There was a failure executing the receive pipeline - Attempted to access an unloaded AppDomain

I was redeploying my BizTalk project after making a little changes in my orchestration. I tested my web service and eventually I got the following error in my Error Log.
There was a failure executing the receive pipeline: "Microsoft.BizTalk.DefaultPipelines.PassThruReceive, Microsoft.BizTalk.DefaultPipelines, Version=3.0.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" Source: "Unknown " Receive Port: "ReceivePortPost1" URI: "/RecRq.asmx" Reason: Attempted to access an unloaded AppDomain.
Well this error occurs when you have published the web services and BizTalk does not recognize the change in the web services. You can reset the IIS and it works. No need to restart the host instances. As a good practice always publish the web services when the orchestrations which are being published as a web service are stopped or in an unlisted state so this error will not occur.

Original Post