Why has my request failed with `invalid_client`?

An invalid_client relates to theclient_idor the client_secretbeing invalid.

Please confirm that these are valid and that you are in the corresponding Live or Sandbox environment.

Note that the client_id and client_secret are different in both environments. You can find more information in our docs.

Solution

Check if your client_id is correct. You can check it in the Console.
Check if your client_secret is correct. You should have kept this in a safe place when downloading the file.
If you hover your mouse above the client_id & client_secretin Postman, it should match the ones from the Console:
If you have lost the client_secret, you can always generate a new one through the TrueLayer Console, under App Settings → Reset Client Secret. Remember to save your client-secret somewhere safe and memorable and replace it everywhere in your application.