That doesn't sound right, what troubleshooting steps have you tried so far? If you haven't already, try reinstalling the app and restart your phone. If that doesn't work, send us a screenshot of the error so we can check. Let us know how it goes.
Thanks for clarifying. Can you check if your Chrome browser is up-to-date: https://yt.be/help/te4Q ? If it is, try clearing cache and cookies instead: https://yt.be/help/Cko1 . Let us know how it goes.