In SharePoint Designer when creating a new external content type to a webservice on SAP using the following steps:

  1. Navigate to the external content type section->new content type-> External system "click here to discover external data sources and define operations"
  2. Add connection->data source type ="wcf service"
  3. Enter url in the "service metadata url" and "service endpoint url"
  4. Try to connect.

While trying to connect, you encounter the following error:

"Cannot connect to Business Data Connectivity Metadata Store.”

The server was unable to process the request due to an internal error.  For more information about this error, either turn on IncludeExceptionDetailInFaults ..."

You may also see the following items logged in the event log:

Source: SharePoint Foundation

Event ID: 8085

Task Category: Business Data

Level: Error

"The BDC Service application is not accessible.  The full exception text is: The  server did not provide a meaningful reply; this might be caused by a contract mismatch, a premature session shutdown or an internal server error."

And

Source: SharePoint Foundation

Event ID: 8082

Task Category: Business Data

Level: Critical

"The remote certificate is invalid according to the validation procedure"

Resolution

The cause of this issue is generally a connectivity issue with the external data source (SAP).  In particular this case is that that the root certificate authority for the domain of the server that is hosting the custom webservice was not added to the trusted root certificate store.  To resolve this you need to go to Central admin | Security | Manage Trust and add the trusted Root certificate that was exported from the SAP system.  You should then be able to go back to SharePoint Designer and correctly create the external content type successfully.

References

Event ID 8082:

http://technet.microsoft.com/en-us/library/ff519268.aspx

Event ID 8085:

http://technet.microsoft.com/en-us/library/ff519266.aspx