Error Occurred: This Route Work invocable action did not create a valid Pending Service Routing. Exception in Salesforce

The exception "Error Occurred: This Route Work invocable action did not create a valid Pending Service Routing. Exception in Salesforce" might be due to following reasons

1. Check whether you are hard coding in Salesforce Flows.
For example, if you are hard coding SkillId, Routing configuration Id, etc., then the Ids will be different across the orgs.

You can avoid hard coding directly in the flow by using Custom Labels.