NavigationTiming - NotRestoredReasons

[yoavweiss]

Description

The NotRestoredReasons interface of the Performance API provides report data containing reasons why the current document was blocked from using the back/forward cache (bfcache) on navigation.

Specification

https://html.spec.whatwg.org/multipage/browsing-the-web.html#document-state-not-restored-reasons

web-feature

https://web-platform-dx.github.io/web-features-explorer/features/bfcache-blocking-reasons/

Test Links

https://wpt.fyi/results/performance-timeline/not-restored-reasons?label=experimental&label=master&aligned

Additional Signals

Positive Mozilla position: mozilla/standards-positions#766
No official WebKit position: WebKit/standards-positions#154

The feature would enable developers to understand why their sites are not being stored in the BFCache across browsers, enabling them to make their back/forward navigations faster.

[github-actions]

This comment was automatically generated based on the information you provided. Please don't edit it.

No web features (from the web-features project) were found in your proposal. If your proposal doesn't correspond to a web feature, that is fine.
Otherwise, please update your initial comment to include web-features: <feature-id>.
To find feature IDs, use the web-features explorer.

[captainbrosset]

There's actually a web-features entry that matches this proposal: https://web-platform-dx.github.io/web-features-explorer/features/bfcache-blocking-reasons/
@yoavweiss if you edit your initial comment to mention this URL in it, the above comment will auto-update with additional information.

[yoavweiss]

@yoavweiss if you edit your initial comment to mention this URL in it, the above comment will auto-update with additional information.

Updated, thanks!!

[wpt-interop]

Thank you for proposing NavigationTiming - NotRestoredReasons for Interop 2026.

We want to let you know it was not selected to be part of Interop this year.

On behalf of the entire Interop team, thank you for submitting it for consideration. We got many more proposals than we could include in this year's project, necessitating some difficult choices. Please note this should not be taken as a comment on the technology as a whole, or our willingness to consider it for Interop in the future. We appreciate the work you put into your proposal, and would welcome your participation in future rounds of Interop.

Posted on behalf of the Interop team.