Progress bar must declare NO_OUTPUT_BUFFERING

The easiest way to reproduce the problem is running this script: https://github.com/brendanheywood/moodle-tool_heartbeat/blob/master/progress.php Try it commenting out the NO_OUTPUT_BUFFERING, with debug developer enabled... you should get a debugging message. To check the behaviour on the affected files , you'll need some data to ensure that the progress takes long enough to execute. Example: 1) Go to a subject 2) Click import on the menu 3) Select another subject that has enough data so the progress bar does not end too fast 4) next next ... 5) perform backup You should see the progress increasing slowing, before the patch it was hanging until completed You may want to repeat the test for the other affected files. Finally, ensure unit tests and behat tests are passing ok.