There is no reliable way to know either future or past Daylight Saving Time (DST) transition hours for any country. This leads to the effect that one hour during transition is skipped or happens twice when time is transitioned forward and backward, respectively. It, in turn, makes scheduled Tasks not run or run twice if they are scheduled to execute in transition hour. Depending on Task design this may lead to unwanted consequences.
Solution
As a solution for this problem Coordinated Universal Time (UTC) can be used in Advanced tab of Task Scheduler properties. This, however, will lead to shift of schedule relatively to local time, e.g., the Task will be executed at different local times (say 3am after spring forward transition and at 2am after fall backward transition), but always at the same UTC time. Additional benefit of using UTC is to synchronize Task running in different time zones.
Alternatively, Daylight Saving Time Transition effects can be avoided by not scheduling any Tasks to happen during transition period.
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If you have any questions, please do not hesitate to contact our support team.