WARNING: GTB is currently not correctly exporting subtasks

Some time after early February 2019, the Google Tasks server has changed the order in which tasks are returned, which has broken how GTB handles subtasks.

NOTE: If you have used GTB since early February 2019 using any format except those listed below, your backup may not contain subtasks!

As at 4 Mar 2019, I am working on a fix, but in the interim, the only GTB export formats which are including all subtasks are;

Unfortunatly, none of these formats are supported by GTI, but at least all your tasks will be backed up.

All subtasks can be displayed using
Display all tasks as a single web page, suitable for printing
by enabling
Display parentless, invalid and corrupted tasks?

Note, however, that subtasks will probably be displayed;

Alternatively, Google Tasks can be exported in JSON formatting using Google Takeout

Google Tasks Backup can be used to export or display Google Tasks
This application uses Google authentication to access your Tasks data. The permission for this application will be displayed as "Google Tasks Backup - Tasks" in your list of Authorised Sites, Apps, and Services, and can be revoked there at any time.