# Critical path broken in one browser: first 30 minutes checklist

Source: https://releasefailures.com/incidents/critical-path-broken-in-one-browser/
Content version: 1.0.0
Verified on: 2026-10-22
Licence: CC BY 4.0

Definition: A core flow fails in one browser or version after a build or polyfill change.
- [ ] FM-01 Ask the reporting user or support for the exact browser and OS version, then reproduce on that version or a simulator.
- [ ] FM-02 Load the same page in other browsers to confirm the failure is limited to one browser.
- [ ] FM-03 Open the browser console on the affected version and record the script error, such as an unsupported regular expression.
- [ ] FM-04 Roll back the deployment when the core page fails in the affected browser and no tested fix is ready.
- [ ] FM-05 After the rollback, load the page again on the affected browser version and confirm it renders.
- [ ] FM-06 Tell affected users which browser and version are failing and which other browser works until the fix ships.
- [ ] FM-07 Post a status update that names the affected browser, the page and the time of the first support ticket.