On this page
Use case
Sub-tasks can be used to structure your work. But keeping parents and sub-tasks in sync can be hard.
In the following use case the parent issue get's transitioned to In Progress, if one of the sub-tasks are being transitioned to In Progress.
Configuration
Add the Transition issue post function to the desired transition or create a new transition in the sub-task workflow.
You might want to add the post function to the transition from To Do to In Progress in the sub-task workflow.
Target issue*
Choose Parent issue
Mode
Choose Transition to status and select the In Progress status from the dropdown list.
Adapt the status according to your needs!
Make sure that the selected status can be reached by the parent issue.
If, e.g. the parent issue is in status To Do, there must be a transition (or a global transition) to In Progress in order to tranistion the parent issue.
If there is no transition, the parent issue won't be transitioned.
Conditional execution
The conditional execution is needed so that the parent issue only will be transitioned if it is in status To Do. If it is in another status, the transition shouldn't take place.
Enter the following expression:
%{parent.status} = "To Do"
Adapt the status according to your needs.
Screenshots
Screencast
Related use cases
STAFF PICK STAFF PICKUse case JWT feature Workflow function Parser functions Label Fast-track transition issues assigned to the project lead 
Transition issue Keep the status of an issue and its linked issues in sync 
Keep the status of parents and sub-tasks in sync (post function use case) Transition issue Reopen parent issue, if a sub-task is reopened Start Progress on parent, if sub-tasks are started
If you still have questions, feel free to refer to our support team.
