Dev Mode Activation.

There's a subscription and an 'app' you have to purchase/download off of the Microsoft Store and online in order to activate the developer console on an Xbox One. You can no longer just 'access' the dev console without purchasing the subscriptions and app.

Details about this should be on the Xbox Creators website. I'll also link you the step by step for activation and deactivation here:

https://docs.microsoft.com/en-us/windows/uwp/xbox-apps/devkit-activation

https://docs.microsoft.com/en-us/windows/uwp/xbox-apps/devkit-deactivation

Here are the Xbox Creators links too!

https://developer.microsoft.com/en-us/store/register/

https://www.xbox.com/en-US/developers/creators-program/

Here you go:

How to activate Dev Mode on your Xbox One console

You may gain some insight by taking a look at the following link.

support.xbox.com/.../developer-mode-activation-app-faq

There is a fee involved just so you know.

What if I don't have a Developer Center account?

You must have a Developer Center account before you can activate the Developer Mode Activation App on your console. There is a fee to create your Developer Center account. For more information, go to

dev.windows.com/en-us/registration/AccountInfo to create your Developer Center account.

Yup, the developer mode just give able for you to start apps from the Visual Studio on your Xbox.

But also you can't to start games from your account in DevMode

Hm is it still working? There is a link to Partner Center. Let me find this out for you. I believe you have to register your app developer with this link: https://developer.microsoft.com/en-us/store/register

All the information is there.