When trying to link my Microsoft account to my PSN account I was met with the same error as hundreds of other people over the past two years. Claiming that my Microsoft account is already linked to a PSN account, which it isn't and never has been. I removed minecraft from my PS4 and reinstalled it. I then created a brand new email address and Microsoft account. I tried to login with this new Microsoft account and had the same error, the email and Microsoft account were no older than five minutes, therefore making it impossible for them to already be linked to a PSN account.