http://developers.de/blogs/damir_dobric/archive/2009/10/29/dtc-transaction-manager-exception-from-hresult-0x80070005.aspxError Description When working with Ado.Net Entity Framework, you may get following error: Exception: The underlying provider failed on Open.    at System.Data.EntityClient. EntityConnection.OpenStoreConnectionIf (Boolean openCondition, DbConnectionenCommunityServer 2008 SP1 (Build: 30619.63)