Gamertag change impossible on any platform (error 1372)

Hello,

I'm trying to change my gamertag with no success. The issue I have is similar to this one, in the sense that I get the same error (but I'm not in the same exact use case) :

https://answers.microsoft.com/en-us...gamertag/64d61b26-ad3c-4ea8-b2f9-eb6d52bde970

I'm mostly using the browser tool to change your gamertag :

https://social.xbox.com/changegamertag

When I enter the desired gamertag, it shows what it will look like ("Gamertag#1234") but when I confirm that I want to change and click on the "Modify my gamertag" button that show up in the pop-up, nothing happens. After a while, I decided to inspect the call with my browser and discovered the call actually responds with a 400 error :





So it seems that the service states that the user is already in use. But then, why is the tool suggesting that the username is actually available ? If, for instance, I try to ask to change to the gamertag of a friend (meaning : I know it's not available), I get blocked before the screen showing me what my new gamertag will look like.

I tried :

• Doing to the same in private navigation
  
• Doing to the same in two others browsers where I never actually logged in with my Microsoft account before
  
• Doing the same on my Xbox One S
  
• Doing the same on different mobile browsers
  
• More weirdly, I tried doing the same with a similar Gamertag, only replacing a "O" with a "0", only to see if the problem might be the gamertag I'm aiming for. I got the "this is what the gamertag will look like" page (without suffixes "#1234" this time)...but I ended up with the same error code.
  

So it looks like something is broken with my account and gamertag changes.

What can I do ?

:)