KNOWLEDGE BASE

Scheduled Tasks Run One Hour Late or Early the Day of the Daylight Saving Time Change


Published: 02 Dec 2013
Last Modified Date: 07 Apr 2017

Issue

On the day of the Daylight Saving Time change, scheduled tasks run one hour late or one hour early.

Environment

Tableau Server

Resolution

This is expected behavior. The day of Daylight Saving Time change, scheduled tasks will run one hour ahead or behind schedule, depending on the direction of the time change. The following day, scheduled tasks will run at the correct times.

Cause

The schedule for scheduled tasks is calculated by number of minutes after midnight rather than at a specific hour value; for example, 4:00 AM is the equivalent of 240 minutes after midnight. On nights when Daylight Saving Time switches, 240 minutes after midnight will not be 4:00 AM. Instead, it will be either 5:00 AM (when the clock is moved forward) or 3:00 AM (when the clock is moved back). This discrepancy occurs for just one day. After one day, the schedule will again run at 4:00 AM as expected.
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