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CORS is the server's permission policy verification by the browser on different origin requests. `Access-Control-Allow-Origin: *` is not a safe solution for all issues; in requests with credentials, a specific origin, `Vary: Origin`, allowed method/header and OPTIONS response must be managed together.
Turkey (Turkish)
Germany (German)
Worldwide (English)
Blocked by CORS policy
No 'Access-Control-Allow-Origin' header
Response to preflight request doesn't pass access control check
Credential is not supported with wildcard originCORS is the server's permission policy verification by the browser on different origin requests. `Access-Control-Allow-Origin: *` is not a safe solution for all issues; in requests with credentials, a specific origin, `Vary: Origin`, allowed method/header and OPTIONS response must be managed together.
Apache, LiteSpeed, Plesk proxy, or NGINX-only setup - do not wait for the `.htaccess` result.
Back up the current file with the date; Find the directive and line in the Apache/LiteSpeed error log.
Do not change redirect, rewrite, header and access rules all at the same time.
Use curl to measure status, Location, Content-Type, and redirect count, and also check cache layers.
Do not use 'Access-Control-Allow-Origin: *' in the API where credentials are used.
Meaning: The response to the request does not include the origin in the 'Access-Control-Allow-Origin' header.
Possible cause: mod_headers not found or rule does not match.
Meaning: Wildcard used in Cookie/Authorization request.
Possible cause: *` and credentials together.
Meaning: Preflight is being redirected to another URL.
Possible cause: HTTPS, www or auth redirect.
Meaning: Authentication preflight is being blocked.
Possible cause: Auth middleware or Basic Auth.
Meaning: Access-Control-Allow-Headers listesi eksik.
Possible cause: Authorization or custom header.
Meaning: The request method is not in the allowed list.
Possible cause: PUT/PATCH/DELETE eksik.
Meaning: Apache, PHP and CDN are adding the same header.
Possible cause: Multiple management points.
Meaning: CDN/font response on the domain does not allow origin permission.
Possible cause: Webfont cross-origin.
No matching record found with this expression.
curl -sSI -H 'Origin: https://app.example.com' https://api.example.com/data | grep -iE '^HTTP|access-control|vary:|location:'CORS response headers.
curl -sS -i -X OPTIONS https://api.example.com/data -H 'Origin: https://app.example.com' -H 'Access-Control-Request-Method: POST' -H 'Access-Control-Request-Headers: Authorization, Content-Type'OPTIONS shows the status and permission headers exactly.
apachectl -M 2>/dev/null | grep headersShows whether the Apache headers module is loaded.
grep -RniE 'Access-Control-Allow|Header (always )?set|header\(' . /etc/apache2 /etc/httpd 2>/dev/null | head -n 120Finds CORS definitions on Apache and PHP side.
curl -sIL -X OPTIONS https://api.example.com/data -H 'Origin: https://app.example.com' -H 'Access-Control-Request-Method: POST' | grep -iE '^HTTP|^location:|access-control'This indicates whether the preflight request is a redirect.
curl -sSI -H 'Origin: https://www.example.com' https://cdn.example.com/fonts/site.woff2 | grep -iE '^HTTP|content-type|access-control|vary:'Displays font file MIME and CORS headers.
Header always set Access-Control-Allow-Origin "*"
Header always set Access-Control-Allow-Credentials "true"SetEnvIf Origin "^https://app\.example\.com$" CORS_ORIGIN=$0
Header always set Access-Control-Allow-Origin "%{CORS_ORIGIN}e" env=CORS_ORIGIN
Header always set Access-Control-Allow-Credentials "true" env=CORS_ORIGIN
Header always merge Vary "Origin"Header set Access-Control-Allow-Origin "%{HTTP_ORIGIN}e"Header always set Access-Control-Allow-Origin "https://app.example.com"
Header always merge Vary "Origin"Header set Access-Control-Allow-Methods "*"Header always set Access-Control-Allow-Methods "GET, POST, OPTIONS"
Header always set Access-Control-Allow-Headers "Content-Type, Authorization"Header always set Access-Control-Allow-Origin "*"
<?php header('Access-Control-Allow-Origin: https://app.example.com'); ?>Manage CORS headers either in Apache or in the application layer only.A fixed or controlled origin allowlist can be applied using mod_headers.
Dynamic tenant/origin control can be more secure in the application layer.
May add Edge or proxy headers and share incorrect responses between cache origins.
No. NGINX does not read `.htaccess` files. The rule must be translated to a `server` or `location` configuration.
Usually not; Apache evaluates the `.htaccess` file on each request. However, a reload or restart is required for VirtualHost, module, or AllowOverride changes.
A dated backup of the existing file should be taken, the active document root verified, and the change tested on staging or during low-traffic periods.
In cPanel it is usually inside `public_html`, in Plesk inside `httpdocs`; addon domains and subdomains may have a different document root.
LiteSpeed supports most rules through Apache compatibility; some module and handler behaviors may differ.
Full directive and line record in Apache/LiteSpeed error log. The file should be restored according to the log instead of being deleted randomly.
Domain should not be added directly without verifying domain, document root, proxy, WordPress, and server structure. Examples should be adapted and tested.
We examine redirection, rewrite, CORS, access and 500 errors with logs in cPanel, Plesk, LiteSpeed, WordPress, custom PHP and WISECP structures.