Error "Tasklists not found" when trying to PUT new task in (shared) list that user has no write access to

What did you try to do?

Create tasklist in account 1, do not tick 'edit' Share with account 2 Use app with account 2, add task in new tasklist Sync

What did you expect to happen?

A sensible error to tell me I have no edit rights on that calendar/tasklist

What actually happened?

Error notification 'Tasklists not found'.