The Task Scheduler and clock changes

ubuysa

The BSOD Doctor
When I installed Windows 10 1903 back in May I setup all my regular tasks (mostly related to auto backup) in the Task Scheduler. For reasons that I can't explain (or just because I'm stupid) when I set the time trigger for my tasks I checked the 'Synchronise across time zones' box. All my tasks ran perfectly - until we had the clock change last Sunday - my backup tasks have been failing since then.

Checking the next run times for my tasks showed that they were scheduled an hour earlier than I'd specified. This matters on my system because the first task is to switch my external backup drive on, the last task is to switch it off. My problem was that the Macrium backup schedule (created by Macrium Reflect) was triggering at 2am as expected but the (manually created) task to switch the external drive on and off were occurring an hour earlier, so the external drive was switching off in the middle of the Macrium backup. Doh!

I have since learned, and the purpose of this post is to let others know too, that if you check the 'Synchronise across time zones' box the trigger time is stored as a UTC time (UTC is the same as GMT) and that's why my tasks were occurring an hour earlier after the clock change. If you leave the 'Synchronise across time zones' box unchecked the trigger time is stored as local time which changes automatically of course with the clock change.

The moral of this story is don't check the 'Synchronise across time zones' box unless you really do want the trigger time to be independent of the clock changes!
 
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