User:KHarlan (WMF)/Blog/Diagnosing and fixing a Flow production error with the help of X-Wikimedia-Debug

outline


 * 1) Overview of the problem: T187861
 * 2) reproducible in production, but not locally in vagrant
 * 3) hypothesis (https://phabricator.wikimedia.org/T187861#4135959) but not able to verify
 * 4) diagnostic code merged, still no help
 * 5) use X-Wikimedia-Debug extension to profile the problematic request and identify which parts of the codebase are executed https://phabricator.wikimedia.org/T187861#4692882
 * 6) Set up replication delay and verify the problem locally https://phabricator.wikimedia.org/T187861#4692882
 * 7) Fix the bug: https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Flow/+/469623