Bug #101507 MySqlCommand.Cancel throws NullReferenceException for a Closed connection

• Submitted: 8 Nov 2020 2:06
• Modified: 8 Nov 2020 4:35
• Reporter: Bradley Grainger (OCA)
• Status: Verified
• Category: Connector / NET
• Severity: S3 (Non-critical)
• Version: 8.0.22
• OS: Microsoft Windows (10)
• CPU Architecture: Any

[8 Nov 2020 2:06] Bradley Grainger

Description:
When MySqlCommand.Cancel is called for a command associated with a closed (or disposed) MySqlConnection, it throws a NullReferenceException. I would expect it to silently succeed. If an exception must be thrown, ObjectDisposedException or InvalidOperationException would be more appropriate than NullReferenceException.

System.NullReferenceException
   at MySql.Data.MySqlClient.MySqlConnection.get_ServerThread()
   at MySql.Data.MySqlClient.MySqlConnection.CancelQuery(Int32 timeout)
   at MySql.Data.MySqlClient.MySqlCommand.Cancel()

How to repeat:
var connection = new MySqlConnection("...");
var command = connection.CreateCommand();
command.Cancel();

// *** OR ***

var connection = new MySqlConnection(csb.ConnectionString);
connection.Open();
var command = connection.CreateCommand();
connection.Close();
command.Cancel();

[8 Nov 2020 4:35] MySQL Verification Team

Hello Bradley,

Thank you for the report and test case.
Verified as described.

regards,
Umesh