Short answer: In Prefect 3.x you don’t need `catchup=false`—the scheduler never backfills missed slots. After an outage, Prefect will only create runs from “now” forward. There’s no catchup flag to set. Useful notes: - This is the default behavior in 3.x. Missed scheduled times during the outage will not be created when the server comes back up. - If you want to tweak how far ahead the scheduler pre-populates future runs, adjust these settings (env vars shown with defaults): -

PREFECT_API_SERVICES_SCHEDULER_MIN_RUNS=3

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PREFECT_API_SERVICES_SCHEDULER_MAX_RUNS=100

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PREFECT_API_SERVICES_SCHEDULER_MIN_SCHEDULED_TIME=1h

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PREFECT_API_SERVICES_SCHEDULER_MAX_SCHEDULED_TIME=100d

You can also change profile values with:

prefect config set PREFECT_API_SERVICES_SCHEDULER_MIN_RUNS=1

References: - Schedules in Prefect 3 - Settings and profiles - Source (scheduler creates runs from current time forward): prefect/server/services/scheduler.py If you’re seeing runs get created for past timestamps anyway, let me know—happy to help trace whether those were manually triggered, created before the outage, or something else.