This is not a server error (404, 500). It is a client-side refusal . The request never actually left your browser.
The “Navigation Failed” Paradox: Debugging HTTP Requests in an HTTPS-Only World This is not a server error (404, 500)
// Option C: Just use a relative path if on the same origin fetch('/api/data'); If the browser is trying to access your http:// resource because your server is misconfigured, you can train the browser to never use HTTP again via HTTP Strict Transport Security (HSTS) . You cannot fix this by telling your users
HTTPS-Only mode forces the browser to automatically upgrade every request to HTTPS. If the upgrade fails (or if you explicitly hardcode http:// ), the browser throws an error instead of falling back to unsafe HTTP. You cannot fix this by telling your users to turn off HTTPS-Only mode. Instead, you need to fix your code or infrastructure. Fix 1: Use Protocol-Relative or Absolute HTTPS URLs (The Easiest) Never hardcode http:// or https:// in your frontend code. Use protocol-relative URLs (starting with // ) or absolute paths. 2026 | Reading Time: 4 minutes
April 14, 2026 | Reading Time: 4 minutes