Symptom
When running a version of a flow as a child flow, you receive the error " Update the child flow for action 'Run_a_Child_Flow' to end with a response action."
Cause
Running an Experlogix flow as a child flow requires a "Respond to a PowerApp or flow" action at the conclusion of the flow.
Solution
Add the required "Respond to a PowerApp or flow" action at the conclusion of the flow.