Hi @Lee_Whitworth, welcome to the Asana Community Forum! Thanks for sharing your feedback with us. We already have a thread on this topic: Mark all subtasks complete before allowing tasks to be marked complete - #38 by Bastien_Siebman. Some customers have shared workarounds and integrations that can help you achieve this, I recommend you to have a look at the comments.
We don’t have updates to share about this feature at the moment but we’ll update the thread as soon as we have any news.
@Bastien_Siebman
I totally agree with you that nothing is simple in the tech world or project management.
But at the same time, Asana introduced the subtasks concept to customers. People are using this functionality and in my opinion, the team should dedicate resources to improve this feature or correct previous logical mistakes.
Right now my team needs to build internal process workarounds to fix this issue. Which means that we are the ones bearing the costs.
The 4-year mark of this thread is coming up and really no solution from Asana. 
Those little tools that allow for project scanning and fixing are not what we all need.
We just need the very basic feature that a subtask needs to be completed before the parent task can be completed.
Right now I am manually creating dependencies for every task/subtask relation, which is very time-consuming.
I think the setting we’re all waiting for should be project-setup-based: Some users might not need or even want this feature. Then toggle it OFF. Default should be: subtask needs to marked complete before allowing tasks to be marked complete.
Can this pls be the last comment on this thread? Thank you! 
What you describe would break many workflows, so I strongly disagree this should be an existing feature. And I wouldn’t want it to be a setting to activate or not, cause that would slow down the dev team as it would complicate the product.
Disable the possibility to mark a task COMPLETE if the subtasks are not. At least warn the user.
Hi @renato3 and welcome to the community!
There is actually already a Product Feedback request for this feature; you can add your vote for it here:
(Also @Marie @Emily_Roman @Rebecca_McGrath will probably merge this post into that other thread.)
Thanks @Phil_Seeman! I’ve gone ahead and merged this thread with the main topic to consolidate feedback.
Thanks for sharing your feedback with us, @renato3!
It is also a big problem for us and prevents accountability in our flow. Is this something that is looked into or has the decision been not to pursue any change on this topic?
Big issue here too it a pop up to warn that some subtask are still not completed would be a must! Please provide an update on this topic!
Sub-tasks are sub-parts of a task, so obviously, it makes absolutely no sense to be able to mark a task complete without having completed its sub-tasks…
Task: Create Human
Sub-task: Arms - completed
Sub-task: Legs - completed
Sub-task: Torso - completed
Sub-task: Head - NOT completed
Mark “Task: Create Human” as completed with no head? LOL
Solution!
I just discovered, correct me if I’m wrong, that if you create sub-tasks as TASKS, mark them as dependents to the actual TASK and then move them into the TASK as sub-tasks, they will prevent the TASK to be marked as completed until all the sub-tasks are all completed.
Hi @Maxime2
When using the detail view, if you try to close a task dependent on another one not performed yet, it gives a warning sign that some tasks have to be performed upfront, are you sure it’s solved?
However I agree, using the list view or the My Task view and click directly on the icon task to perform, nothing is blocking you to do it.
I’d like the same window to appear to prevent tasks to be completed without a clear check before.
You mean when you manually force the software to change the status of the task?
Well the issue was closing without warning. This way you can’t close without manually forcing the software to change the status, and even then you get a warning…
You can always force close any activity, even with dependents. You can always force the system to change the status of tasks, that’s true in any software
When I saw the first comment was "Apr 17’ I thought to myself “oh this is a recent bug.”. I am shocked that such an important feature is left unattended to since April 2017. 
Adding my voice here. Our company would love for there to be more control around completing tasks (and completing blocked tasks) before subtasks (or dependencies) are complete!
A solution could be as simple as adding a warning that there are still incomplete tasks, or as complex as toggling an option on to prevent the task from being completed. Users don’t always have easy visibility into nested subtasks assigned to others, so this will be a good check for them.
Would love to have this feature! An alternative would be automatically marking the task complete once all of it’s subtasks are complete - I assumed there was a way to set this up with automations but was surprised when it wasn’t an option (we have a premium subscription, not business, so I’m not sure what rules I could build myself there).
I can’t believe this issue has still not been fixe 4 years on. Come on Asana team, this is a no brainer and is causing undue time in having to make the parent dependent on sub tasks…
Add my vote 100x!
At the MINIMUM, throw an alert same as dependencies do - it seems relatively simple to update that exact same error alert with a “if dependencies are not complete OR there are incomplete subtasks - show alert.”
At maximum, on project or workspace level, whichever is more feasible code-wise, the setting(s) as to expected behavior - from not allowing parent tasks to be marked complete to only throwing an alert.
Possible workaround:
Create a subtask and then set this task as a blocking dependency for the parent task. This way the parent task cannot be marked as “complete” without resolving subtasks first.
ClickUp does warn and ask a confirmation from the user if he tries to complete the task without completing the subtasks first. There is also an option to not to display the warning in future.