At a glance

Define the school's time periods (bell schedule) before generating.

What causes this error

The scheduler needs a bell schedule — a list of named time slots (periods) that define when lessons can take place. This error appears when no periods are defined.

How to fix it

Go to School Config → Periods and add at least two default periods (e.g. 08:00-08:45, 08:50-09:35). Each period needs a start time and a duration.

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