Symptoms
Deployment Failed due to Reference Error of missing Activity
Diagnoses
Previously, I have renamed Activity and I config action on form again but when I want to deploy, it is displaying the error where Form is Referencing Activity (old) that could not be found.
Resolution
A coldfix has been provided to resolve the missing activity errors. Additionally, you deleted action that error reference in form on the tables Form.ActionItem and Form.ActionInstance from your end. After which, you were able to deploy fine.