Precondition: At least one extra language is added in the system (e.g. Polski pol-PL), pl siteaccess defined.  

Steps:

1. Go to eZ Platform folder. 
2. Go to Translations tab and add new translation in Polski.
3. Go to URL tab.
4. Add new URL alias: testpl for Polski.
5. Try to reach eZ Platform folder using added url alias.

Result: Error 404 Page not found. 

No route found for "GET /pl/testpl"