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 Periods configuration 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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