Why is HTTPS required?

Service Workers can intercept network requests. HTTPS ensures the script is not tampered with during delivery, preventing man-in-the-middle attacks.

How do I test Service Workers locally?

Browsers allow Service Workers on localhost without HTTPS. Use http://localhost:port for development.

Browser Service Worker Registration Failed Error

Warninggeneral browser

Overview

Service Worker registration failure prevents PWA features like offline mode and push notifications from working, typically due to HTTPS or scope issues.

Key Details

Service Workers require HTTPS (except on localhost for development)
The Service Worker script must be served from the same origin as the page
Scope determines which pages the Service Worker controls
Registration can fail silently without visible error on the page
Check DevTools > Application > Service Workers for registration status

Common Causes

Website not served over HTTPS
Service Worker JavaScript file returns 404 or has syntax errors
MIME type of Service Worker file is not application/javascript
Service Worker scope does not match the page URL path
Browser blocking Service Workers due to privacy settings

Steps

1Open DevTools (F12) > Application tab > Service Workers to see registration status and errors
2Ensure the site uses HTTPS (or localhost for development)
3Verify the Service Worker file URL returns 200 with correct MIME type
4Check the browser console for specific Service Worker error messages
5In Firefox, check about:debugging#workers for active Service Workers

More in General Browser

browser-net-err-cert-common-name-invalidBrowser NET::ERR_CERT_COMMON_NAME_INVALID — SSL Name Mismatch

Error

Frequently Asked Questions

A JavaScript file that runs in the background, enabling features like offline caching, push notifications, and background sync for Progressive Web Apps.