SSIS: How to fix 'Can't get lock on variable or deadlock occured' error when you are trying to handle exception using Script Component

Issue:

If you've a Script Component in the Control Flow, which is writing to LogFile (DtsVariable), and an exception occurs, and if you Exception Handling Component also using the same LogFile (DtsVariable) to log error to the file then you enter a deadlock scenario. It happened because the Script component was still holding the lock but flow jumped to the Exception Handler. All that needs to be done was to un lock variable before we jump to the Exception Handler Block.

Resolution:

Try

...

Catch ex As Exception
Logfile.WriteLine("Exception Occured: " + ex.Message)
Dts.Variables.Unlock()
Dts.TaskResult = Dts.Results.Failure
Throw New Exception(ex.Message)
End Try

Additional Reading:

Reusable Functions for Reading and Writing Variables in SSIS Script Tasks

http://www.developerdotstar.com/community/node/512