Getting {"error": "invalid_grant", "error_description": "invalid code verifier"}

arcade

I'm using PKCE flow https://www.dropbox.com/developers/documentation/http/documentation#oauth2-token

in my react native expo app for generating the token.

I'm able to generate code & state value successfully after hitting this url https://www.dropbox.com/oauth2/authorize 

But when i trying to get the access token using below

```

const params = new URLSearchParams({
      code,
      grant_type: "authorization_code",
      client_id: DROPBOX_CLIENT_ID,
      code_verifier: codeVerifier,
      redirect_uri: redirectUri,
    });

    console.log("PKCE params", params.toString());

    const response = await fetch("https://api.dropboxapi.com/oauth2/token", {
      method: "POST",
      headers: {
        "Content-Type": "application/x-www-form-urlencoded",
      },
      body: params.toString(),
    });

```

I'm getting this error {"error": "invalid_grant", "error_description": "invalid code verifier"}

I've verified that the code challenge and code verifier are correct and are passed correctly into the request. 

Stuck on this for hours now, need help. Thanks

DB-Des

Hi @arcade 

When you use the official Dropbox JavaScript SDK, you do not need to implement all of the logic for this process yourself. The SDK will do most of the work for you. You can find examples of using this here.  More specifically, you can find an example of implementing PKCE on the back end here: https://github.com/dropbox/dropbox-sdk-js/blob/main/examples/javascript/PKCE-backend/code_flow_example.js or the front end here: https://github.com/dropbox/dropbox-sdk-js/tree/main/examples/javascript/pkce-browser