SSIS Package Validation Error when Executed From Windows Task Scheduler
I could not resolve this issue and changed my approach to utilize a SQL Job instead of running the package directly from a powershell script.

Summary of solution:


SQL Job with one Job Step
The Job Step executes the SSIS package


To run a SQL Job with a custom you must also create:


an instance-level Credential
a Proxy Account which should be mapped to the Credential


I still wonder what's different about this approach versus the 'interactive' approach listed above. Both approaches run with the exact same identity and privileges!

For an in-depth description of the steps required to configure a SQL Job, look at this example code for Automated Deployment of a SQL Job and Job Step.

Hope this helps someone else in the same situation -