DOC 1 ERROR: There was no endpoint listening at net.pipe://localhost/Microsoft/Dynamics/GP/eConnect/EntityOperations that could accept the message. This is often caused by an incorrect address or SOAP action. See InnterException, if present, for more details.
I was actually surprised at how detailed it was, as Integration Manager errors are usually fairly generic. This message was very specific and to the point.
The adapter I was using was an eConnect adaptor, so the first port of call was to check in Services to make sure the eConnect for Microsoft Dynamics GP 2010 Integration Services was running:
As you can see from the screenshot, above, the service was NOT running. I started the service and retried the integration and it worked without error.