NotRestoredReasons API reason name change

concepts

1. Live reason probe

   Reads PerformanceNavigationTiming.notRestoredReasons for the current navigation and prints the reasons in the new names.

2. Rename table + RUM linter

   The migration view: full before/after table of reason renames, plus a paste-your-code linter that flags references to the old strings before they break your dashboards.

3. Reason name migration tool

   Paste a JSON dump of pre-135 notRestoredReasons and watch every legacy reason name get rewritten to the 135 spelling. Useful for rewriting archived RUM data so historical charts still match the live API.

4. BFCache Eligibility Checker

   Toggle page features (open WebSocket, Web Lock, IndexedDB, Cache-Control: no-store) and see which renamed NotRestoredReasons codes would block BFCache. Reads the live API from the current navigation, and includes a RUM normaliser for handling both old and new names during rollout.

why it shipped

We are going to change the names reported in NotRestoredReasons API so that they match the specified names. NotRestoredReasons API has been launched for 6 months now.

references

• ChromeStatus entry
• Spec