access control allow origin

How-To

How to Fix CORS Error ‘No Access-Control-Allow-Origin’ Header in 2026

Fix the CORS error ‘No Access-Control-Allow-Origin header is present’ — what causes it, how to configure the server correctly, and how to handle preflight requests.

July 30, 2026 5 min read

How-To

How to Fix CORS Preflight OPTIONS Request Failing in Production

Fix failing CORS preflight (OPTIONS) requests in production — server config, credentials, allowed headers, and nginx/Express solutions with examples.

July 12, 2026 5 min read

How-To

How to Fix ‘CORS Policy: No Access-Control-Allow-Origin Header’ Error

Fix CORS errors in every scenario — Express.js, nginx, browser fetch, credentials mode, preflight requests, and the security reason CORS exists.

July 2, 2026 5 min read