System.Data.EntityException: The underlying provider failed on Commit

Question

Using Entity Framework, I received a number of the following exceptions last night in one of my applications:

System.Data.EntityException: The underlying provider failed on Commit. ---> 
System.Data.SqlClient.SqlException: Timeout expired.  The timeout period elapsed prior 
to completion of the operation or the server is not responding.     
    at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) 
    at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning()     
    at System.Data.SqlClient.TdsParserStateObject.ReadSniError(TdsParserStateObject stateObj, UInt32 error)
    at System.Data.SqlClient.TdsParserStateObject.ReadSni(DbAsyncResult asyncResult, TdsParserStateObject stateObj)
    at System.Data.SqlClient.TdsParserStateObject.ReadNetworkPacket()     
    at System.Data.SqlClient.TdsParserStateObject.ReadBuffer()     
    at System.Data.SqlClient.TdsParserStateObject.ReadByte()     
    at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler,SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)     
    at System.Data.SqlClient.TdsParser.TdsExecuteTransactionManagerRequest(Byte[] buffer, TransactionManagerRequestType request, String transactionName, TransactionManagerIsolationLevel isoLevel, Int32 timeout, SqlInternalTransaction transaction, TdsParserStateObject stateObj, Boolean isDelegateControlRequest)
    at System.Data.SqlClient.SqlInternalConnectionTds.ExecuteTransactionYukon(TransactionRequest transactionRequest, String transactionName, IsolationLevel iso, SqlInternalTransaction internalTransaction, Boolean isDelegateControlRequest)     
    at System.Data.SqlClient.SqlInternalConnectionTds.ExecuteTransaction(TransactionRequest transactionRequest, String name, IsolationLevel iso, SqlInternalTransaction internalTransaction, Boolean isDelegateControlRequest)
    at System.Data.SqlClient.SqlInternalTransaction.Commit()     
    at System.Data.SqlClient.SqlTransaction.Commit()
    at System.Data.EntityClient.EntityTransaction.Commit()     
    --- End of inner exception stack trace ---     
    at System.Data.EntityClient.EntityTransaction.Commit()     
    at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options)     
    at System.Data.Entity.Internal.InternalContext.SaveChanges()     
    at System.Data.Entity.Internal.LazyInternalContext.SaveChanges()

What's interesting about this error is that the data was actually written to the database. I found a related post on a MS site that seemed to indicate that this was a network related error.

A few questions that I could use assistance on are:

1. What options do I have to trouble shoot this error?
2. Is it more than likely network related or could the DB be a suspect?
3. How can I tell from the code whether the transaction really did complete?
4. Should I query the DB on this error to check if success or simply retry the transaction?
5. If I do retry the transaction, how can this be accomplished automatically with Entity Framework or do I simply catch/retry?
6. What other items should I be looking at?

Thanks in advance.

UPDATE

Using Ignite for SQL we were able to determine that a secondary SQL process from another group was monopolizing the CPU preventing our application from functioning properly. In short, we're moving forward with adding a secondary server to prevent further conflicts between the two teams.

What's still interesting about the exception is that the transaction actually succeeded rather than failed.

Answer 1

My bet is that the success response from the transaction commit command was not sent (or not sent fast enough) causing an exception in your code. A kinda crazy edge case. Exceptions of this kind dont necessarily mean that the actual execution of the command failed just that there was A failure.

In the same way if there was a problem sending the response from a webservice call it wouldn't necessarily imply that any side effects of that call were not applied.