# Flag default flips on missing config: pre-release checklist

Source: https://releasefailures.com/incidents/flag-default-flips-on-missing-config/
Content version: 1.0.0
Verified on: 2026-10-21
Licence: CC BY 4.0

Definition: A missing or unreadable flag config falls back to the wrong default.
- [ ] PR-01 Compare the flag set of every region with the release's flag list and fail the release when a region such as the EU lacks a flag the update depends on. (test class: Configuration and environment tests)
- [ ] PR-02 Read the default value of each flag in the release and confirm it equals the current production value. (test class: Configuration and environment tests)
- [ ] PR-03 Confirm the flags that route internal traffic default to the RPC path and not to the legacy HTTP path. (test class: Configuration and environment tests)
- [ ] PR-04 Start new containers with the external flag service blocked and confirm they keep the last known production flag values. (test class: Chaos and resilience tests)
- [ ] PR-05 Drop the flag streaming connection on running containers and confirm their flag values stay unchanged. (test class: Chaos and resilience tests)
- [ ] PR-06 Record DNS query volume and connection setup time during the blocked-flag-service test and fail the test when either rises above its baseline. (test class: Chaos and resilience tests)
- [ ] PR-07 Halt the rollout when any canary container logs a feature flag initialization error. (test class: Canary and progressive delivery checks)
- [ ] PR-08 Place a canary in each region, including the EU, and compare the share of EU sessions that use the chart formula feature between canary and baseline. (test class: Canary and progressive delivery checks)