解決方法：https://github.com/laravel/passport/issues/221

In your oauth_clients table, do the values you have above exist exactly as you have them in your database?

oauth_clients

id - 3
secret - 3TfJGj4rrvOQvjZkI8dDqx78ouH99F2DuIMKHoKH
redirect - http://consumer.dev/callback

If it doesn‘t exist exactly like that in the database for passport.dev then it will throw the invalid_client error. Please be sure to check that and we will see if any further investigation is needed.

• 還需要查看 oauth_clients 表的 password_client 是否為 1

API Authentication Error: {"error":"invalid_client","message":"Client authentication failed"}