Pages are sometimes protected even before they exist if an administrator thinks that a page with such a title shouldn't be created. (In the English Wikipedia this is called "salting".)

A similar, though technically different, scenario is that the title was blacklisted (TitleBlacklist).

Content Translation uses standard publishing APIs and respects this protection, but it could be communicated more clearly to the users:

• As soon as the page is loaded, a warning could be shown that says something like "A page with this title cannot be published."
• It should also be shown if the translator changes the title to a protected or blacklisted title in the middle of the translation process, but with a delay, because a protected title might come up while typing another legitimate title.
• The reason for the protection can be shown. It's supposed to be given by the administrator who protected it.
• If the title is blacklisted, it should probably be shown differently.
• If a talk page exists, a link to it can be given. (But frequently it doesn't exist.)
• We may consider mentioning that a page can be published with a different title, but we should also remember the Beans rule :)

See also https://www.mediawiki.org/wiki/Topic:T4du1yykzeqi9afz