How to Debug TypeError: Failed to fetch in Next.js?

[developer-choi]

Problem Description

When a request fails in a Next.js application, the error message TypeError: Failed to fetch sometimes appears in the browser console. We know that this error can occur for multiple reasons, such as CORS restrictions, network failures (reference).

We run a global service, and today, we encountered this issue specifically in the Philippines. The application was working fine before, and no deployment changes were made recently.

🚨 The real problem is that developers have no way of knowing which specific cause triggered this error!

Why Is This a Problem?

The developer tools console only shows TypeError: Failed to fetch, without specifying whether the issue is caused by CORS, DNS failure, or a blocked request.
No useful stack trace or debugging information is available, making it almost impossible to determine what went wrong.

Feature Request / Discussion

🔹 Are there ways to extract more details about why fetch() failed, without violating security policies?
🔹 What’s the best way to systematically debug Failed to fetch errors when no meaningful information is provided?

If anyone has effective debugging strategies for this, I’d love to hear them! 🔥