Word of the functionality appeared over the weekend in a post from Reddit user LiamHing. After entering the Settings > System menu, pressing Left Bumper, Right Bumper, Left Trigger and Right Trigger in quick succession, you'll unlock a hidden Developer Settings menu item. Within that, you'll find an option called Enable devkit. Those who do will need to enter a Sandbox ID for the console, which is apparently available to registered developers.
Reddit user XboxOneDev, whose username is tagged as an Xbox One developer on Reddit, warned against enabling the functionality in a comment on the thread.
"Please don't mess with anything here for the time being, especially the sandbox ID," XboxOneDev wrote. "You risk putting your box into a boot loop."
XboxOneDev acknowledged that he has "no idea how far along the ID@Xbox program is. There are many concerns such as privacy, security, stability etc.., that need to be sorted out before we can allow anyone and everyone to simply sideload an app onto their box."
Corporate vice president at Xbox Marc Whitten revealed in August that "every Xbox One can be used for development," though he clarified to Polygon that the functionality would not arrive with the console's Nov. 22 launch. For more on how Microsoft plans to use the functionality to support developers, be sure to read our interview with Chris Charla, the director of ID@Xbox.
We've reached out to Microsoft for more information about the hidden feature and will update this article with more information as we receive it.
Update: A Microsoft representative told Polygon that it does not recommend that users change the settings and explained how to restore an Xbox One if something goes wrong.
"Changing the settings in this menu is only intended for developers for Xbox One, and this alone does not turn the console into a development kit. We strongly advise consumers against changing these settings as it could result in their Xbox One becoming unusable. Customers who have put their consoles into this developer setting can revert by restoring factory defaults under Settings / System, select Restore Factory Defaults."