# Critical path broken in one browser: pre-release 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.
- [ ] PR-01 Load the web interface on an iOS 16.2 simulator, or the oldest iOS version in the support policy, and confirm it renders past the background picture. (test class: Compatibility tests)
- [ ] PR-02 Parse the production JavaScript bundle against the oldest supported browser versions and fail the build on any regular expression syntax those versions reject. (test class: Compatibility tests)
- [ ] PR-03 Rerun the full browser matrix when a dependency upgrade changes the markdown parsing sub-dependency chain, even when the application diff is small. (test class: Compatibility tests)
- [ ] PR-04 Run the end-to-end test that opens the Files page in every browser listed in the support policy, not only the default test browser. (test class: End-to-end tests)
- [ ] PR-05 Add an end-to-end test that opens a files app view that renders the rich text component and confirms the view finishes loading. (test class: End-to-end tests)
- [ ] PR-06 Schedule a synthetic check that loads the Files page in each supported browser engine against production after every deployment. (test class: Synthetic monitoring)
- [ ] PR-07 Alert when the synthetic Files page check fails in one browser while it passes in the others. (test class: Synthetic monitoring)