Sporadic Asp.net Data Error: "cannot Find Table 0"

Having deployed a new build of an ASP.NET site in a production environment, I am logging dozens of data errors every second, almost always with the error 'Cannot find table 0.' We

Solution 1:

Bumping this old question because we have encountered the same issue and perhaps our solution would give more insight in what causes this.

Essentially this problem occurs in a production environment that is under very heavy load in a Windows service that uses multiple threads to process several jobs simultaneously (100 users use the same DB via ASP.NET web app and there are about 60 transactions/second on older hardware with SQL Server 2000).

No variables are shared, that is connections are opened anew, transaction is started, operations executed, transaction committed and connection closes.

Under heavy load sometimes one of the following exceptions occurs:

NullReferenceException:Object reference notsetto an instance of an
object.
at System.Data.SqlClient.SqlInternalConnectionTds.get_IsLockedForBulkCopy()

or

System.Data.SqlClient.SqlException:
The server failed toresume the transaction. Desc:3400000178

or

New request isnot allowed to start because it should come with valid  transaction descriptor  

or

This SqlTransaction has completed; it is no longer usable

It seems somehow the connection that is within the pool becomes corrupted and remains associated with previously used transactions. Furthermore, if such connection is retrieved from pool then sqlAdapter.Fill(dataset) results in an empty dataset, causing "Cannot find table 0". Because our service would retry the operation (reading job list) on failure and it would always get the same corrupt connection from the pool it would fail with this error until restarted.

We removed the issue by using SqlConnection.ClearPool(connection) on exception to make sure this connection is discarded from the pool and restructuring the application so less threads access the same resources simultaneously.

I have no clue who exactly caused this issue so I am not sure we have really fixed that, maybe just made it so rare it had not occurred again yet.

Solution 2:

I've fought precisely this error message before. The key is that an underlying data method is swallowing a timeout exception.

You're probably doing something like this:

var table = GetEmployeeDataSet().Tables[0];

GetEmployeeDataSet is swallowing an exception, probably a timeout exception, which is why it only happens sporadically - it happens under load. You need to do the following to fix it:

1. Modify the underlying code to not swallow the exception, but rather let it bubble up to the next level so you can identify it properly.
2. Identify the query(s) causing the problem, and then rewrite, reindex, denormalize or throw hardware at the problem. See this for more info: System.Data.SqlClient.SqlException: Timeout expired

Solution 3:

I've seen something similar. I believe our problem had to do with failed sessions being re-used (once the session object failed it went into a poor state and could not recover.) We fixed it by increasing the memory for the session pool and increasing the frequency of the web application recycling.

It also was "caused" by a new version that at first blush did not seem to have any change to cause such an effect. However, eventually it became clear that the logic of the program was opening and closing a lot more connections (maybe 20% more) than it used to. This small change pushed the limit of our prior configuration.

Solution 4:

You might check the SQL Server logs for errors. Or, the Web server event log. It sounds like your connection pool could be out of open connections or your db could be out.

Solution 5:

Which database calls changed between versions?

The error is obviously telling you one of your database calls isn't returning any data on occasion; I can't think of any cases where a code/assembly issue would cause it.