“This SqlTransaction has completed; it is no longer usable.”… configuration error?

Question

I've been working on this for about a day and a half now, and searched numberous blogs and help articles on the Web. I found several questions on SO related to this error, but I didn't think they quite applied to my situation (or in some cases, unfortunately, I couldn't understand them well enough to implement :P). I'm not sure I can describe this well enough for help... but here goes:

We have a .NET app to track our resources. There's an export function to copy a resource to the time tracking system and the billing system; this accesses a stored procedure that links to the time and billing databases.

I recently moved the billing system database to a new server (original server: Server 2003 SP2, SQL 2005; new server: Server 2008 R2, SQL 2008 R2). I have a Linked Server set up that points to the 2008 databases. I updated the stored procedure to point to the 2008 server, and then I got an error about MSDTC and RPC (http://www.safnet.com/writing/tech/archives/2007/06/server_myserver.html). I enabled 'rpc/rpc out' on the Linked Server and set MSDTC to allow Network Access (something like this: http://www.sqlwebpedia.com/content/msdtc-troubleshooting).

Now I'm getting the above, when I try to run the export function: "This SqlTransaction has completed; it is no longer usable." What seems odd to me is that when I just run the stored procedure (from SSMS), it says it completes successfully.

Has anyone seen this before? Have I missed something in the configuration? I keep going over the same pages, and the only thing I found was that I didn't reboot after making the MSDTC changes (mentioned in here: http://social.msdn.microsoft.com/forums/en-US/adodotnetdataproviders/thread/7172223f-acbe-4472-8cdf-feec80fd2e64/).

I can post part or all of the stored procedure, if it would help... please let me know.

Answer 1

I believe this error message is due to a "zombie transaction".

Look for possible areas where the transacton is being committed twice (or rolled back twice, or rolled back and committed, etc.). Does the .Net code commit the transaction after the SP has already committed it? Does the .Net code roll it back on encountering an error, then attempt to roll it back again in a catch (or finally) clause?

It's possible an error condition was never being hit on the old server, and thus the faulty "double rollback" code was never hit. Maybe now you have a situation where there is some configuration error on the new server, and now the faulty code is getting hit via exception handling.

Can you debug into the error code? Do you have a stack trace?

Answer 2

I had this recently after refactoring in a new connection manager. A new routine accepted a transaction so it could be run as part of a batch, problem was with a using block:

public IEnumerable<T> Query<T>(IDbTransaction transaction, string command, dynamic param = null)
{
  using (transaction.Connection)
  {
    using (transaction)
    {
      return transaction.Connection.Query<T>(command, new DynamicParameters(param), transaction, commandType: CommandType.StoredProcedure);
    }
  }
}

It looks as though the outer using was closing the underlying connection thus any attempts to commit or rollback the transaction threw up the message "This SqlTransaction has completed; it is no longer usable."

I removed the usings added a covering test and the problem went away.

public IEnumerable<T> Query<T>(IDbTransaction transaction, string command, dynamic param = null)
{
  return transaction.Connection.Query<T>(command, new DynamicParameters(param), transaction, commandType: CommandType.StoredProcedure);
}

Check for anything that might be closing the connection while inside the context of a transaction.

Answer 3

I have the same problem. This error occurs because conection pooling. When exists two or more users acess the system the connetion pooling reuse a connetion and the transation too. If the first user execute commit ou rollback the transaction is no longe usable.

Answer 4

I have recently ran across similar situation. To debug in any VS IDE version, open exceptions from Debug (Ctrl + D, E) - check all checkboxes against the column "Thrown", and run the application in debug mode. I have realized that one of the tables was not imported properly in the new database, so internal Sql Exception was killing the connection, thus results into this error.

Gist of the story is, If Previously working code returns this error on a new database, this could be database schema missing issue, realize by above debugging tip,

Hope It Helps, HydTechie

Answer 5

In my case the problem was that one of the queries included in the transaction was raising an exception, and even though the exception was "gracefully" handled, it still managed to roll back the entire transaction.

My pseudo-code was like:

var transaction = connection.BeginTransaction();
for(all the lines in a file)
{
     try{
         InsertLineInTable(); // INSERT statement might fail and throw an exception
     }
     catch {
         // notify the user about the error on line x and continue
     }
}

// Commit and Rollback will fail if one of the queries 
// in InsertLineInTable threw an exception
if(CheckTableForErrors())
{
    transaction.Commit();
}
else
{
    transaction.Rollback();
}

Answer 6

Also check for any long running processes executed from your .NET app against the DB. For example you may be calling a stored procedure or query which does not have enough time to finish which can show in your logs as:

• Execution Timeout Expired. The timeout period elapsed prior to completion of the operation or the server is not responding.

  • This SqlTransaction has completed; it is no longer usable.

Check the command timeout settings Try to run a trace (profiler) and see what is happening on the DB side...

Answer 7

In my case , I've some codes after committing the transaction at the same try catch block. an error may led the execution to catch block which contains the transaction rollback. It will show the similar error. For example look at the code structure below :

SqlTransaction trans = null;

try{
 trans = Con.BeginTransaction();
// your codes

  trans.Commit();
//your codes having errors

}
catch(Exception ex)
{
     trans.Rollback(); //transaction roll back
    // error message
}

finally
{ 
    // connection close
}

Hope it will help someone :)

Answer 8

Here is a way to detect Zombie transaction

SqlTransaction trans = connection.BeginTransaction();

//some db calls here

if (trans.Connection != null) //Detecting zombie transaction
{
  trans.Commit();
}

Decompiling the SqlTransaction class, you will see the following

public SqlConnection Connection
{
  get
  {
    if (this.IsZombied)
      return (SqlConnection) null;
    return this._connection;
  }
}

I notice if the connection is closed, the transOP will become zombie, thus cannot Commit. For my case, it is because I have the Commit() inside a finally block, while the connection was in the try block. This arrangement is causing the connection to be disposed and garbage collected. The solution was to put Commit inside the try block instead.