Create a JQL query that will determine if the transition can proceed or not.

Test the JQL in the Issue Navigator first.

No unresolved sub-tasks: parent = XXX-1 and resolution is empty

Add a Conditioned validator to the appropriate workflow transition 

Assumes you have installed the Update on Transition for Jira add-on

Put the JQL query in the JQL Query field

It is likely you need to use one or more substitution variables like %original_key% in place of a specific values you may have used while testing

parent = %original_key% and resolution is empty

Condition by how many issues are found by the query

• %jql_result_count% is the more substitution variable that says how many issues were found

• Put that value in the Condition 1 Value field

• Put 0 in the Condition 1 Regex field

• Likely user cases are:

  • Proceed with the transition if there are 0 issues found - do not select the Negative checkbox

  • Proceed with the transition only if there was at least 1 issue found - select the Negative checkbox

All sub-tasks must be resolved

Condtion 1:
   Value: %jql_result_count%
   Regex: 0

Add a user friendly message that will show if the validator fails

Add appropriate text to the Message field and optionally use substitution variables.

Save the post function

Run a test scenario

• Use How to get problem determination information to debug your scenario if necessary.

• JQL errors will be logged in the JIRA application log. Note: This is the most common cause for problems.

• Remember, the JQL query runs under the user's permission unless you are using Acting user support.