Bug 246622 – Local and Sync storage merged since safari 15

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKit Extensions

[Carlos J.]

Since Safari 15, the extensions local and sync storage seems to be merged into one. This means operations in local storage apply to sync storage and the reverse. This caused the users of of my extensions with more than half a million of downloads to loose all their user settings. To keep compatibility across browsers, the sync and local storage should be separated.

A sample extension can be found via this link:
https://github.com/carlosjeurissen/webext-tech-demo-extensions/tree/main/issues/safari-9723963-merged-sync-and-local-storage

[Carlos J.]

Previously reported as:
https://feedbackassistant.apple.com/feedback/9723963
https://developer.apple.com/forums/thread/693211

[Alexey Proskuryakov]

Thank you for the report! This is not a WebKit issue, but a Safari one. Apple will continue to track it internally.

rdar://84214292

[Timothy Hatcher]

We are tracking bugs in Bugzilla for Web Extensions now as we move extensions support from Safari to WebKit.

But this was resolved in Safari 15.2. MDN has a note.

[Carlos J.]

Thanks for fixing! Where is the note in MDN? Can't seem to find it.

[Timothy Hatcher]

Click on "15" in the "Safari on iOS" column in the table at the bottom of https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/storage/sync

"Safari 15 and 15.1 erroneously store sync items in the local storage area. If unable to locate sync items, check for sync items in the local storage area and do a one-time migration to the sync storage area."