What does "Something went wrong" mean when redeeming an Xbox code?

This generic error usually means one of the following: Xbox servers are temporarily down, there's a browser or cache issue on your end, your Microsoft account has an outstanding unpaid balance, or you're redeeming from the console or app instead of the web. Start by checking https://support.xbox.com/en-US/xbox-live-status. If servers are fine, try redeeming at https://redeem.microsoft.com in a Chrome Incognito window (Ctrl+Shift+N).