• Old app cleanup: Settings > Storage now shows how much space Arc Timeline 3’s old data is using on your iPhone, with a safe way to delete it when you no longer need it. Safeguards make sure everything worth keeping has been copied across first. (BIG-321, BIG-693)
• Improved recording accuracy on underground metro and train lines. (BIG-607)
• Improved timeline item handling around recording gaps, plus other timeline processing refinements. (BIG-444, BIG-585)
• The place merge confirmation now shows each place’s visit count, to help you pick the keeper. (BIG-676)
• Responses in Search can now be copied with a long press. (BIG-561)
• Fixed a date display issue for Japanese and Chinese at larger text sizes. (BIG-673)
• Plus foundations for place categories, coming in a future update. (BIG-513)
Just to be sure, on the Arc V4, the new “Cleanup” function cleans Arc V3 datasets.
Is it right to understand that datas was duplicated between V3 and V4, and thus, that if I cleanup V3 datasets, my timeline will stays unchanged, even about old datas that are related to years ago (prior to V4) ?
Yes, that’s exactly right. When you migrated, your Arc Timeline 3 data was copied into Arc Timeline 4’s own database, so your entire timeline, including all the years from before V4 existed, now lives in Arc Timeline 4’s own storage. The old Arc Timeline 3 files on your iPhone are leftover duplicates.
The Cleanup only deletes those leftover files from the old apps. It never touches Arc Timeline 4’s database, so your timeline stays exactly as it is, all the way back to your earliest years.
There are safeguards too: the delete button stays disabled until the app has verified that migration is complete and the old app isn’t still recording. If it’s greyed out, the note underneath it explains why.
I complete the migrate from arc 3 timeline option in settings of arc 4 but the delete option for the arc 3 data is always not available and the note below says the old apps database contains data that hasn’t been migrated to arc timeline 4.
i have run through the migrate option a few times to no avail. Any idea why this is occurring?
@RnGRRnGR The locked delete button doesn’t by itself mean your migration failed. The deletion feature is deliberately cautious — it refuses to remove the old app’s data while a completeness cross-check between the two databases isn’t satisfied — and there are data shapes where that check stays unsatisfied even after a migration that did its job. One known cause: data the old app itself originally imported from elsewhere (Moves, GPX files, Apple Health workouts) counts on one side of the comparison but not the other. In that situation re-running Migrate won’t move it, so no need to keep trying — the extra runs did no harm, they only cost time.
To see exactly which state yours is in: Settings gear → Advanced → Debug Logs, open the newest log, tap Share log, and email it to matt@bigpaua.com with a link to this thread. The app records that check’s inputs each time it starts, so the newest log carries the exact comparison it ran — from that we can say whether anything actually needs doing. The check’s blind spot is already tracked on our side either way.
Meanwhile there’s no harm in the old data staying put — it’s only occupying storage, and your Arc Timeline 4 data doesn’t depend on it.