How do I update the subtasks based on the parent issue?

[NAW]

Based on the status of the parent, I want to update the subtasks status.

That is when the parent = "completed" status, the subtasks should be = "completed" as well. Do you know if we can do this without using a plugin?

[Boris Georgiev _Appfire_ · Accepted solution]

That's not possible without a plugin. The way to do this is to add a workflow post-function to the workflow of the parent issue type which will transition all sub-tasks to "completed".

Here's a sample of how to do this with script runner:

 https://scriptrunner.adaptavist.com/latest/jira/recipes/workflow/postfunctions/auto-close-all-subtasks.html

and a recent related question https://answers.atlassian.com/questions/38745845

There are also other plugins that you can use to achieve the same result.