Game won't launch on Xbox

Let's keep that as a last resort. Try clearing the personal saved data with these steps:

1. Hit the Guide button on your controller
2. Highlight the NHL 26 icon
3. Hit the Menu button. It's the small one to the right of the guide button with the 3 horizontal lines on it
4. Choose Manage game & add ons
5. Go to Saved data
6. Delete the file with your gamertag on it
   
   

You can also try deleting local saves.

1. Go to Settings > System > Storage devices
2. Go to Clear local saved games
   
   

Let me know if either of these help.