ETL | The No-Brainer Lab

I upgraded a set of SSIS packages from SSIS 2008 R2 to SSIS 2012 and all of them had a smooth upgrade except for one. I had script tasks in almost all the packages which ran succesfully after I upgraded and tweaked them.

There was one package which was giving me trouble and functionally it dealt with moving, loading and deleting files from various folders. I upgraded the script task, updated all references, modified the project paramaters (as I am using the Project Deployment Model) and when I tried to run the package (Debug mode), the following generic error popped up:

Exception has been thrown by the target of an invocation.
at System.RuntimeMethodHandle._InvokeMethodFast(IRuntimeMethodInfo method, Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeType typeOwner)
at System.RuntimeMethodHandle.InvokeMethodFast(IRuntimeMethodInfo method, Object target, Object[] arguments, Signature sig, MethodAttributes methodAttributes, RuntimeType typeOwner)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.RuntimeType.InvokeMember(String name, BindingFlags bindingFlags, Binder binder, Object target, Object[] providedArgs, ParameterModifier[] modifiers, CultureInfo culture, String[] namedParams)
at Microsoft.SqlServer.Dts.Tasks.ScriptTask.VSTATaskScriptingEngine.ExecuteScript()

This error message was very generic and did not help me in tracking down the root cause. I decided to put a breakpoint into the Main() method of my script and tried debugging the package again. I was surprised when the script task opened up in VSTA and reached my breakpoint (which contradicted the generic error message – Invocation Error). The issue was with folder security to access the files.

Hope this helps fellow ETL developers who might come across similar issues with a generic invocation error.

When I develop SSIS packages, I set the connect managers’ connection strings in one of the following ways:

Package Variables reading from an XML config file
Environment Variables
Package Variables whose values are passed from a SQL job invoking the package

I had a set of SSIS packages running for my client using the third option listed above. The packages worked fine for ages until one fine day when they failed. The logs showed the packages had failed validation and I discovered that all the packages had their connection managers’ DelayValidation property set to False. The variable used to set the connection string had a default value pointing to the DEV server. These packages in production were actually trying to validate against DEV database though the connection string was dynamically set via a variable to point to PROD. This was dangerous as the jobs will not run if DEV server was down, which is exactly what had occurred.

Whenever you have a connection string set dynamically using variables, the best practise is to set the DelayValidation property to True for all the connection managers and all the Data Flow Tasks. I found the following blog article to be useful with some quick handy tips.

http://www.louisnguyen.info/Home/ssis-best-practices