Forgive me if this is a duplicate but this pertains to the new API pushed out this morning.

Trying to change IGN capitalization doesn't work at all anymore, not on the minecraft.net website (says the IGN is taken) and it doesn't work on the API anymore either - previously you could've changed the capitalization via the normal API.

Here's the new API error that's returned:

{
  "path": "/minecraft/profile/name/{username}",
  "errorType": "FORBIDDEN",
  "error": "FORBIDDEN",
  "details": {
    "status": "DUPLICATE"
  }
}