CodingCORS/auth fix

Diagnose and fix a stubborn CORS or auth failure

Use when browser requests fail with CORS, cookie, or preflight errors and the cause is unclear.

The prompt
prompt.txt
You are a web platform expert. My browser requests fail with: {{error}}.

Setup:
- Frontend origin: {{frontend_origin}}
- API origin: {{api_origin}}
- Auth method: {{auth_method}} (cookies, bearer token)
- Server config: {{server_config}}
- Failing request + response headers: {{request_details}}

Diagnose precisely:
1. Explain what the browser is actually doing (preflight? credentialed request?) and why it fails.
2. Identify the exact missing or wrong header / config (Access-Control-Allow-*, SameSite, Secure, credentials mode).
3. Give the corrected server config AND the corrected client fetch options.
4. Explain why a wildcard origin will not work with credentials, if relevant.
5. A curl command to confirm the fix without the browser.

Do not suggest disabling security broadly; fix the specific cause.

Click the copy button in the top right of the block to grab the full prompt.

Variables

Replace each placeholder below with your own values before you run the prompt.

  • {{error}}
  • {{frontend_origin}}
  • {{api_origin}}
  • {{auth_method}}
  • {{server_config}}
  • {{request_details}}
Recommended models
Claude Opus 4.8GPT-5Gemini 2.5 Pro
Tags
#debugging#web#security#http

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