The OSM QA Tiles project, hosted by Mapbox, generates vector tiles from OSM data.

Owing to some recent changes in our architecture, the paths from where to retrieve QA tiles have changed. Any file that was earlier found at the path https://s3.amazonaws.com/mapbox/osm-qa-tiles/, can now be found at https://s3.amazonaws.com/mapbox/osm-qa-tiles-production/. If you are using QA tiles generated by Mapbox, please update your code to receive the latest updates.