Thank you. However I am talking about the secret key (P8 format) I have an existing key generated a few years ago that works fine but today the key generation does not seem to work. To check the key, I used the "JWT generator" in the tab "Tools" of "Push notification" inside the Apple developer website. So I generate the key from my Apple account then upload it in the tool and it indicates that the issuer is wrong ! (of course it works fine with my old key)