BizTalk does not recognize change in Web Services

I was redeploying my BizTalk project after making a little change 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 Service and BizTalk does not recognize the change in the Web Services. You can reset IIS and it works. No need to restart the host instances. As a good practice, always publish Web Services when the orchestrations which are being published as a Web Service are stopped or are in an unlisted state so this error will not occur.