The error message you're seeing, "invalid_client", suggests that there's an issue with the OAuth 2.0 client you're using. This could be due to a variety of reasons such as the client not existing, incorrect client authentication, or an unsupported authentication method. Here are a few steps you can take to troubleshoot this issue: 1. Check your registered clients: Make sure the client ID and password are correct. You can list your registered clients using the following command:

bash hydra list clients --endpoint <http://127.0.0.1:4445>

(Source: [Ory Hydra Documentation](https://www.ory.sh/docs/hydra/self-hosted/gitlab#client-wrong)) 2. Check your OAuth 2.0 client configuration: You can check the configuration of your OAuth 2.0 client using the following command:

bash ory get oauth2-client {client.id}

This will show you the whole client (excluding its secret). Make sure the values are correct. (Source: [Ory Hydra Documentation](https://www.ory.sh/docs/hydra/debug#refresh-token-flow-fails)) 3. Check your redirect URL: Make sure the redirect URL you're using is whitelisted in your client configuration. The URLs must match exactly. You can check the whitelisted redirect_uris using the following command:

bash ory get oauth2-client {client.id}

(Source: [Ory Hydra Documentation](https://www.ory.sh/docs/hydra/debug#refresh-token-flow-fails)) If you're still encountering issues after trying these steps, it might be helpful to refer to the [Ory API Reference](https://www.ory.sh/docs/reference/api) for more information on error responses.