Hey Frank, sorry to hear you're hitting a wall with the access token step after successfully grabbing the authorization code—this kind of roadblock is so frustrating when you're trying to get your WordPress Pinterest plugin off the ground. Since Pinterest support can't lend a hand right now, let's walk through the most common culprits behind this failure and how to check each one:

• Double-check every request parameter
  The token endpoint is picky about exact matches, so verify these are all correct:

  • grant_type: Must be set to the exact string authorization_code (no typos here)
  • code: Use a fresh authorization code—these are single-use, so if you've retried before, you'll need to go back to Step 1 to get a new one
  • client_id & client_secret: Copy these directly from your Pinterest app dashboard (even a single extra space or missing character will break things)
  • redirect_uri: This must match exactly what you entered in your app's settings—include http/https, any subdomains, and even trailing slashes if you used them there. A tiny mismatch here is one of the most common causes of failure.

• Confirm your request format
  Make sure you're sending a POST request (not GET) to the token endpoint. Also, Pinterest typically expects the data to be sent as application/x-www-form-urlencoded—not JSON. If you're using a library or curl, double-check that the content type header is set correctly.

• Rule out rate limiting
  Pinterest's API has rate limits, and if you've been retrying multiple times quickly, you might be blocked temporarily. Wait 5-10 minutes, grab a fresh authorization code, and try again.

• Check your app's status
  If you're testing with a production account, ensure your Pinterest app is set to "Live" status. Development-mode apps often have restricted access that can prevent token generation.

• Dig into the error response
  Even failed requests usually include a specific error message that can point you straight to the issue. For example:

  invalid_grant: The authorization code is expired, already used, or doesn't match your client ID/redirect URI
  invalid_client: Your client ID or secret is incorrect
  redirect_uri_mismatch: Your redirect URI doesn't match the one configured in your app

If you can share the exact error message you're receiving, we can narrow this down even more. But these steps cover most of the common issues I've encountered with Pinterest's token flow.

内容的提问来源于stack exchange，提问作者Frank