Thread:Project:Support desk/ switch: Lang doesn't work for log-out visitor/reply (5)

"setlang" is a URL parameter provided by Extension:UniversalLanguageSelector. In all wiki's hosted by Wikimedia Foundation, persistent language selection for anonymous users is disabled. This feature is enabled by default in ULS, but disabled in Wikimedia wikis because of worries about cache fragmentation. "uselang" is a URL parameter provided by core, that only works for a single page view.