Project Online shuts down on 30 September: no licence, no export
Microsoft switches Project Online off on 30 September and PWA sites stop being available. But what decides whether you make it in time is not in the announcement: it is in the service description, which requires a live Plan 3 or Plan 5 subscription in the tenant for ANY interaction. Which means the licence you were going to drop to save money during the migration is the one you need in order to export. There is also a second 120-day clock written somewhere else, the PWA is a SharePoint site and not a calendar, and the destination's published limits explicitly exclude your plan.
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