This page lists when and how production wikis were affected by mistakes made in development (major bugs which needed a SWAT deploy etc.), so we can get an overview of how often this happens and what are the typical reasons behind it.
Really bad breakages (site outage, major performance impact on all users etc.) should be mentioned on wikitech:Incident documentation as well.
- 2014-04-08: a SWAT deploy of some breaking OOjs UI changes  broke the reuse panel in MediaViewer. Fixed in another SWAT deploy .
- 2014-04-10: MediaViewer links to Commons in the file reuse panel got deployed sooner than the handling of those links did, which combined with another bug resulted in an empty black screen when someone tried to use those links (#423). Fixed in SWAT .
- 2014-04-10: a site configuration issue (no Commons favicon in repoinfo API) and the lack of proper fallback handling resulted in one of the main buttons disappearing. Fixed in SWAT , proper fallback handling will be pushed with the regular updates.
- 2014-04-10: the metadata panel was broken on enwiki (#437, #438). Apparently a ResourceLoader caching issue, disappeared after running
- 2014-04-14: the button to open MediaViewer on file pages (#199) was deployed to Commons and small wikis, but it only worked when MV was enabled. Noticed the next day, fixed in a SWAT deploy .