How to prevent issues from being closed while the sub-tasks are still open in Jira

[Anil Perugu]

How to prevent issues from being closed while the sub-tasks are still open in Jira?

I am using "Team managed software" template.

[Chris Buzon]

This is NOT possible in the way you are looking for, but you can do something similar 
through automation rules, but not through the rules in the workflow editor. 

Instead, open your project settings and find the automation section.  
You'll start on "library" tab, but you want to switch the Rules tab and then you'll be able to create one like this:

*note - you can do this in a lot of ways, I'm just choose the force the ticket back into In Progress, but you'll have to consider how you've set your project up for this to work:

[Chris Buzon]

To clarify, I am not "preventing" it here, that's not possible at all in Team managed projects, you need to use validators or conditionals in a Company managed project to actually prevent it, as far as I can tell.

[DWedekind]

For a server environment (unsure if it is the same within the cloud):

If your are using Script Runner you will find a condition called 

"All sub-tasks must be resolved [ScriptRunner]" while editing a transition.

otherwise it is a condition called "Sub-Task Blocking Condition". Here you can choose the status a subtask must have before the parent task can be resolved.

[Trudy Claspill]

This is not the same in Jira Cloud for Team Managed projects.

Jira Server is similar to Jira Cloud Company Managed projects. but Team Managed projects have a very different workflow management process.