TYPO3 Core

The page module allows to switch between languages as well as between the "Columns" and "Languages" mode.

However the available possibilities, e.g. the special -1 option ("All languages") depends on the selected page and site. For example, in a single-language site, the -1 option won't be available.

Therefore, the page module evaluates the currently stored options for the user when accessing any page in the page module and automatically falls back to defaults, on invalid options. This automatic fallback should however not be persisted since this breakes workflows. It's just sufficient to resolve invalid options on the fly .