Hello, As you may know, Wikibase currently does not normalize pagenames/filenames on save (e.g. underscores in the input for properties of datatype Commons media are allowed). At the same time, Wikidata’s quality constraints extension <https://www.mediawiki.org/wiki/Extension:WikibaseQualityConstraints> triggers a constraint violation after saving, if underscores are used. This is by design as to long-established <https://www.wikidata.org/wiki/Template:Constraint:Commons_link> Community practices. As a result, this inconsistency leaves users with unnecessary manual work. We will update Wikibase so that when a new edit is saved via UI or API, and a pagename/filename is added or changed in that edit, then this pagename/filename will be normalized on save ("My file_name.jpg" -> "My file name.jpg"). More generally, the breaking change is that a user of the Wikibase API may send one data value when saving an edit, and get back a slightly different (normalized) data value after the edit was made: it is no longer the case that data values are either saved unmodified or totally rejected (e.g. if a file doesn’t exist on Commons). Since this guarantee is being removed with this breaking change announcement, we may introduce further normalizations in the future and only announce them as significant changes, not breaking changes. The change is currently available on test.wikidata.org and test-commons.wikimedia.org. It will be deployed on Wikidata on or shortly after September 6th. If you have any questions or feedback, please feel free to let us know in this ticket <https://phabricator.wikimedia.org/T251480>. Cheers, Lucas Werkmeister -- Lucas Werkmeister (he/er) Full Stack Developer Wikimedia Deutschland e. V. | Tempelhofer Ufer 23-24 | 10963 Berlin Phone: +49 (0)30 219 158 26-0 https://wikimedia.de Imagine a world in which every single human being can freely share in the sum of all knowledge. Help us to achieve our vision! https://spenden.wikimedia.de Wikimedia Deutschland - Gesellschaft zur Förderung Freien Wissens e. V. Eingetragen im Vereinsregister des Amtsgerichts Berlin-Charlottenburg unter der Nummer 23855 B. Als gemeinnützig anerkannt durch das Finanzamt für Körperschaften I Berlin, Steuernummer 27/029/42207.