Created on child’s account. Tried to create 2nd child’s account and get a something went wrong message after inputting birthdate. The kid is 12. This has taken my entire Christmas morning trying to troubleshoot this. So freaking frustrated.
It's possibly still working despite the error message and may have created the account.
The other thing to try, if you are trying to set it up using the phone app, is to do the setting up from a PC by logging into Family Center on the web (click the link, then click the blue "Go to Supervision" button at the top of the page, then you can "add a family member"). I had issues adding my child's profile to a new headset using the app/headset, but it worked when I did it via the web.
But you can contact MetaStoreHelp by clicking their name and then "Message" on top-right of their profile, or contact support here.
