Sorry, the request and approval was on chatter and the contact received an email. But, I still get the error message from above saying "no process was found."
I finally passed this. I set the validation on the case status of New, created a new case, clicked submit for approval, but didn't approve it. Then submitted the challenge and it went through.
I was also receiving this error. I felt like I tried everything but what finally worked for me was deleting the Entry Criteria. When creating the Approval Process, in Step 2, I Specified Entry Criteria with the Field "Case: Escalated" equals True since it was a Case Escalation procedure. In the challenge instructions, "No entry criteria is required for this approval process" means DO NOT specify entry criteria.
-Shashi