How do I confirm my CORS fix works?
Test from your actual React app in the browser, not just Postman. Postman does not enforce CORS, so it cannot confirm your fix works. Only the browser can tell you whether the response is now allowed.
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Cross-check this information using these trusted sources:
More FAQs in A CORS Debugging Checklist for React Developers
Confirm it is CORS in the console, identify your frontend origin, check the server response headers in the Network tab, verify preflight is handled, check credentials if relevant, apply the right fix on the server or via a proxy, and test from the browser.
Read the browser console. A CORS error specifically mentions cross-origin or Access-Control headers. Other errors during a fetch, like network errors or 404s, are not CORS even though they happen during a request.
Look for Access-Control-Allow-Origin set to your origin or a wildcard. If it is missing or set to a different origin, the server is not allowing you. Also check that OPTIONS preflight requests are handled with the right headers.
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