How can I make sure an user closes sub-tasks before closing the main task

[Jux]

Currently I noticed that some of the assignee close a task without closing the sub-tasks. Can't seem to find a way to lock the task closure until all sub-tasks are closed.

So currently I am working on instilling discipline but wondering is there a way to make sure that happens on Jira?  

[Alexey Matveev]

Hello,

Use the Sub-Task Blocking Condition. (go to workflow -> conditions)