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Debugging CORS with Chrome DevTools Network and Issues tabs
Filter failed requests, compare preflight vs main response headers, and copy as fetch for reproduction.
1 min read
devtoolsdebuggingcors
Network filters
Enable Preserve log when redirects happen during OAuth or login flows.
Click the failed row and inspect Response Headers—missing Access-Control-Allow-Origin is the usual smoking gun.
Reproducing for backend teams
Copy as cURL or fetch from DevTools to share exact headers your browser sent.
Note whether credentials were included; that tightens Allow-Origin rules.