When attempting to run a web service in a form or connect to a SharePoint site from Composer, you receive the error message "The underlying connection was closed: an unexpected error was received."
The Winshuttle Foundation components make many calls between themselves when certain actions are taken (web services, opening a solution in Composer). If the Winshuttle Foundation SharePoint site cannot be reached by the SAP Integration Manager or Composer can't reach the Foundation site, this message will be returned.
This often happens in a load balanced environment if one node is experiencing issues. Requests to that node die and the session is terminated, causing the error above.
Ensure the Winshuttle Foundation SharePoint site is reachable consistently from every other Winshuttle SAP Integration server.