TYPO3 Core

baseVariants for languages (https://docs.typo3.org/m/typo3/reference-coreapi/master/en-us/ApiOverview/SiteHandling/AddLanguages.html#base) can currently only be edited by editing the site config .yaml directly. (Which is not the focus of this issue, but does anybody know if there is an feature request for this already?)

But if a site contains language baseVariants they will be removed from the .yaml after saving the site config in the backend.

languages:
 -
    languageId: '2'
    base: 'https://domain.ch/'
    baseVariants:
      -
        base: 'http://ch.stagingdomain.de/'
        condition: 'applicationContext matches "#^.*/Staging#"'
      -
        base: 'https://domain.ch.test/'
        condition: 'applicationContext matches "#^.*/Local$#"'

This could be solved by adding the missing configuration fields to the GUI (see above, maybe there is a feature request already for that?).