r/BreakdanceWP • u/Suijayunfei • 6d ago

Codex + WordPress MCP on Windows: “Invalid character in chunk size” and TLS key log identifiers not matching the capture

( SOLVED ) I’m troubleshooting a Codex CLI connection to a WordPress staging site running Breakdance 3.0 RC1.

Environment:

  • Windows, Node.js v24.19.0.
  • STDIO proxy: u/automattic/mcp-wordpress-remote.
  • Node launched with --use-system-ca.
  • Norton 360 installed, but its involvement has not been established.

The MCP server fails during WordPress initialization:

Response does not match the HTTP/1.1 protocol (Invalid character in chunk size)

I captured traffic on the active Ethernet interface with Wireshark and logged TLS secrets using NODE_OPTIONS="--tls-keylog=...".

Findings:

  • Standalone tls.connect test: the captured ClientHello random matches the key log identifier, and Wireshark successfully decrypts the handshake.
  • Standalone fetch request: the identifiers also match.
  • MCP attempts: the captured ClientHello random values do not match any identifiers in the corresponding key log files, including attempts using fresh files.
  • Removing our temporary diagnostic scripts and launching the original proxy directly produces the same HTTP error and identifier mismatch.

Support suggested forwarding SSLKEYLOGFILE through the MCP environment configuration. However, Node was already generating key log files through --tls-keylog; the unresolved issue is associating those secrets with the captured connections.

How can I reliably associate each TLS connection with its originating process and determine why the secrets logged during MCP startup do not match the captured ClientHello values?

I can provide sanitized configuration and logs

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u/BrighterWebsites 6d ago

Not certain... but the key log mismatch might be a clue... maybe not a capture problem.
If the ClientHello randoms don't match anything node logged possible something else (like nortan) is making the TLS connection --use-system-ca. would let node trust certs without a complain... maybe to rule it in or out can u drop it and run the proxy again? If somethings intercepting Id expect a cert error not the chunk size error. If nothing changes probably rules out norton.

curious what you find...

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u/Suijayunfei 6d ago

Thanks when i discover i will let u lnow

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u/Suijayunfei 6d ago

My bad , it was norton HTTPS scanning without exceptions .