Son’s child account won’t sign in.

Sign into the Family account with your account and remove the account of your son, and then send an invitation as a child account to your sons email. And he can join the FAMILY as a child.

https://account.microsoft.com/family/

Are you an adult account or possibly a child account? You may need to fix that.

Also:

When an adult and a child are both signed in on
Xbox One, the console enforces the content limits that are set for the child
account. This means that if your child or teen is restricted from watching a movie with mature content, you won’t be able to watch that movie while your child is signed in

If there is a child account on the Xbox make sure it is not signed in.

Hello - my son is not signed into a Microsoft account on the switch, it’s a gmail account.

So if we add an email won’t it start him over?

This is happening to my son's account too. I looked up the code in the support code seazrch. It says:

Error 83118853 occurs when you try to sign in to Xbox Live using a child account

Problem:

You see the following error and message when you try to sign in to Xbox Live using a child account:

Before you can sign in here, you'll need to sign in at Xbox.com.

An adult will also need to sign in so they can give permission.

Code: 83118853

This means that the parent account must provide permission for each associated child account (under age 13) before the child can access Xbox Live.

Solution:

To resolve this issue, have the child account sign in to Xbox.com. Then, when prompted, the parent account associated with the child account should sign in to Xbox.com and give permission for the child account to sign in to Xbox Live.

So I did this. I signed into my son's account on xboxlive.com, it gave the prompt then I signed in. When I signed in it said I had to charge my current pay method $0.50. Ya I know that's not a lot but they already know I am an adult and I have made several
purchases through the xbox including my Live membership. I do not want it charging me for this. It is unnecessary. I have been a member for about 5 years, my son for at least the last 3. He was logged in earlier today and it didn't ask this. I want my son's
account working without me having to give someone more money.

hi there i would suggest if the steps below dont work head over to https://support.xbox.com/ and chat to an advisor there to walk you through the steps in the mean time

If you’re receiving this error code when trying to sign in with a child account, it may mean that the child account isn’t a member of your family.

Child accounts that aren’t members of a family won’t be able to use the Xbox Live service until they’ve been added to a family. To verify whether the child account is a member of your family, sign in to your Microsoft account and see if the child’s
account is listed on the Your family page.

Sign in to your account

If the child account is a member of your family, go to the next solution. If the child account isn’t a member of your family, you’ll need to add them so they can sign in and use Xbox Live. For info, see:

Add family members on Xbox One

or

Make sure that your privacy settings are set so that the child account can sign in. To do so, have the child sign in to their account at www.xbox.com. Then, when prompted, the adult account associated with the child account should sign in to www.xbox.com
and give permission for the child account to sign in to Xbox Live.

Sign in to Xbox.com account