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Browser Agent / Auth session

Browser agent loses session after login

The automated browser logs in but the next action uses a fresh or different session.

Error text / 报错原文

  • session lost after login
  • cookies not preserved
  • login loop

What it means

The automated browser logs in but the next action uses a fresh or different session.

Most common causes

  • Agent launched a new browser profile
  • Cookies are not persisted
  • SSO redirects to a different domain
  • Tool switches between headless and visible browser modes

Fastest fix

  • Reproduce the smallest failing case outside the agent.
  • Confirm auth, session, and transport before changing app code.
  • Disable unrelated tools or servers and retry once.
  • Capture the exact timestamp, client version, and raw error text.

Safe fix

  • Keep secrets in environment variables or the platform secret store.
  • Use least-privilege scopes and read-only tools by default.
  • Add validation around manifests, schemas, and callback URLs.
  • Document the working local and production configuration.

What not to do

  • Do not paste OAuth tokens or session IDs into public logs.
  • Do not bypass TLS, CSP, or permission prompts as a permanent fix.
  • Do not enable every MCP tool globally just to make one task pass.

Diagnostic commands

node --version
npx @playwright/mcp@latest --help
curl http://127.0.0.1:9222/json/version

Related tools

Related errors

Sources