Hey there! I’ve dealt with this exact problem when building apps that pull tweets from private Twitter accounts—let’s break down the fix step by step:

• First: Get Authorization from the Private Account Owner
  Protected tweets are only accessible to authorized apps and approved followers. You need to:

  1. Walk the account owner through your app’s OAuth authorization flow, making sure to request the required permissions: specifically tweet.read and users.read (these are mandatory for accessing protected timeline content).
  2. If it’s your own private account, head to your Twitter Developer Dashboard, navigate to your app’s permissions settings, and confirm that your app is granted access to your protected content.

• Second: Use the Correct Authentication Method
  When calling the https://api.twitter.com/1.1/statuses/user_timeline.json endpoint, Bearer Token authentication won’t work for private accounts—it only grants access to public content. Instead, you must use OAuth 1.0a with a user-specific access token and access token secret to sign your request. This tells the API that your app has explicit permission to access that private account’s data.

• Third: Double-Check Your Request Parameters & Error Codes
  Make sure you’re passing the correct screen_name or user_id for the private account in your request. If you get an error response, use the status code to narrow down the issue:

  • 403 Forbidden: Almost always means your app doesn’t have authorization to access the protected content, or you’re using the wrong authentication method.
  • 401 Unauthorized: Check that your access token and secret are valid, and that your app has the required permissions enabled.

• Quick Testing Tip
  If you’re testing with your own private account, try revoking and re-authorizing your app to refresh permissions—this often fixes odd authorization glitches that can block access.

内容的提问来源于stack exchange，提问作者Mehul_MG