resync_required

HTTP 410: Resync required

When it occurs

The cursor sent to GET /v1/changes names a point older than the tombstone retention window (180 days, SYNC-05); the server can no longer promise every entry between there and now is still around to replay.

What to do next

Drop the stored cursor and do a full resync, starting from cursor=0 (or omitted), the same as onboarding a brand-new copy of the data.