Preflight Request
An OPTIONS probe request that a browser sends automatically before issuing a non-simple cross-origin request, used to confirm whether the server permits the actual request method, headers and origin.
Timeline (last 90 days)
When a browser-side agent initiates a paid call, if the preflight request fails due to a missing header name, no 402, 400, or timeout will appear in the server logs, because the request never left the browser.
A missing request header in Access-Control-Allow-Headers causes the preflight to fail, the actual business request is never sent, and the server produces no error logs.
A preflight request is an OPTIONS probe that the browser automatically sends before a non-simple request; requests using methods such as PUT/DELETE, custom request headers, or a non-standard Content-Type trigger a preflight.
All Facts (3)
When a browser-side agent initiates a paid call, if the preflight request fails due to a missing header name, no 402, 400, or timeout will appear in the server logs, because the request never left the browser.
50%UnverifiedA missing request header in Access-Control-Allow-Headers causes the preflight to fail, the actual business request is never sent, and the server produces no error logs.
50%UnverifiedA preflight request is an OPTIONS probe that the browser automatically sends before a non-simple request; requests using methods such as PUT/DELETE, custom request headers, or a non-standard Content-Type trigger a preflight.
50%