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Posts Tagged "ADO.NET"

SqlCommand oddity raises NullReferenceException on an otherwise valid query

Bit of a head scratcher for this one. I was working on some ADO.NET code that involved calling a stored procedure with many (10k+) table valued parameter rows being passed in. Occasionally, I’d see a bug where ExecuteNonQuery would result in an exception with the following stack trace (I tried it with ExecuteReader and ExecuteScalar just to be sure as well):
System.NullReferenceException was unhandled by user code
Message=Object reference not set to an instance of an object.
at System.Data.SqlClient.SqlCommand.OnReturnStatus(Int32 status)
at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)

I knew for sure the command object was not null, and so I started looking at the Reference Source. It seemed the parameter collection was the cause of the issue.
I enabled CLR debugging in Visual Studio and dove in. The most relevant block of that function is here:
In my case, count was…