At a glance

A lesson's planned day or time no longer exists in the current school period configuration.

What causes this error

The timetable being regenerated contains lessons with a planned day or start time that no longer exists in the current school period configuration. This typically happens when the school's period schedule was modified after the timetable was last generated.

How to fix it

Open the saved timetable and update its period configuration to match the current school data, then retry the generation.

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