Error message for obtaining access_token

[kuangxiang]

Error message for obtaining access_token 

api : https://api-m.paypal.com/v1/oauth2/token

{

    "error": "invalid_client",

    "error_description": "Client Authentication failed"

}

What is usually the reason for this situation

[kuangxiang]

Firstly, I was able to obtain it successfully in the sandbox environment. However, after replacing it with the official version of the client ID and secret, the error mentioned above occurred. I have repeatedly verified that the client ID and secret are correct