An Xbox Live service alert acknowledges that some people on Xbox One are experiencing problems redeeming their beta codes. Microsoft is working with Activision to get the problem fixed "ASAP."
"Thank you for being patient while we work," Microsoft said. "We'll post another update when more information becomes available."
Code redemption on PC appears to be unaffected.
The Black Ops III multiplayer beta for Xbox One and PC will run through August 30. Activision has not said if it plans to extend the beta as a result of these issues. On PS4, Activision extended to Black Ops III beta for an extra day, but this was not related to any beta code redemption problems.
Currently, access to the Xbox One and PC Black Ops III multiplayer beta is available only for people who preordered the game. Activision opened up the PS4 beta to everyone in its final days, but the company hasn't said if it will do the same on its new platforms.
For more on the Black Ops III beta, check out GameSpot's five tips to help you make the most of the new abilities and mechanics.