Software⏱️ 2 min read📅 2026-05-31

How to Fix error 400 Error – Exposing localhost to the internet via tunneling (using ngrok): HTTP error 400: bad request; invalid hostname

Quick Answer: Check ngrok configuration and ensure the hostname is correct.

To expose localhost to the internet via tunneling using ngrok, first ensure that your local IP address is accessible. You can do this by running a simple HTTP server and accessing it through its IP address.

⚠️ Common Causes

  • Incorrect ngrok configuration or invalid hostname.

🛠️ Step-by-Step Verified Fixes

Method 1: ngrok Configuration

  1. Step 1: Run ngrok and specify the correct URL for your local website.

Method 2: Update Hostname

  1. Step 1: Ensure that the hostname in ngrok is set to a valid and accessible domain.

💡 Conclusion

By following these steps, you should be able to expose your website running on localhost to the internet using ngrok. Ensure that you configure ngrok correctly and update the hostname if necessary.

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