Fix CORS before you blame the SDK
TL;DR The bug is usually the preflight ( OPTIONS ), not your fetch call or the client library. Access-Control-Allow-Origin: * and credentials: 'include' never work together. Echo an exact origin from an allowlist — not a wildcard — when the SPA and API sit on different hosts. Your SPA lives on https://app.example.com . Your API lives on https://api.example.com . You open DevTools, hit a button,…
CORS (Cross-Origin Resource Sharing) errors occur when a web application, running on one domain, tries to make requests to a different domain, and the server does not allow it. In this case, the issue lies with the server-side configuration, not the client-side SDK or fetch call. To resolve the problem, ensure that the API on https://api.example.com allows requests from the SPA running on https://app.example.com by specifying the correct Access-Control-Allow-Origin header in the response.
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