On occasion I get the following error when trying to synchronize from SQL Express to SQL Server using Sync Framework 2.1. Once a client gets this error they have to reiniti
This happened to me syncing between 2 SQL Azure databases. The initial cause was that the slave DB grew larger than it's provisioned size. I increased the size, but it was a good 20 minutes before the sync stopped throwing the error
try to enable Sync Fx tracing and check if Sync Fx logs the original exception. if i remember it right, the exception is normally raised when the db connection is lost. you should be able to retry the sync though without re-provisioning the scope.