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E_INVALID_PROTOCOL_FORMAT
E_INVALID_PROTOCOL_FORMAT (0x83760002) means the Windows protocol component encountered protocol data does not satisfy WebSocket framing or handshake syntax. The Windows WebSocket component rejects HTTP handshake information or frame-level data because the required protocol representation is malformed. For E_INVALID_PROTOCOL_FORMAT, identify the failing layer before changing HTTP, TLS, or application payload settings.
Keep raw protocol evidence
- Preserve response headers exactly as received before normalization.
- For frame failures, retain opcode, FIN/RSV bits, mask direction, and payload length.
- Record selected extension and subprotocol indices passed to handshake completion.
Frequent boundaries
| Area | Inspect |
|---|---|
| Handshake headers | Upgrade, Connection, Sec-WebSocket-Accept, version, extension, and subprotocol syntax. |
| Frames | Control-frame size, fragmentation rules, reserved bits, masking, and length encoding. |
| Text payload | UTF-8 validity is separate from application JSON validity. |
Isolation
- Complete a handshake with no extensions or subprotocols
- Replay a standards-compliant single text frame
- Add negotiated features one at a time
Do not retry blindly
A malformed handshake or frame is deterministic. Reconnection without correcting the bytes can create a tight failure loop and hide the first useful capture.
Validate framing before payload interpretation
Preserve FIN, RSV, opcode, mask, payload-length encoding, masking key, and fragmentation history for the first rejected frame. Control frames have tighter rules than data frames, and a proxy may remask or reframe traffic, so compare the bytes at the endpoint that actually returned the HRESULT.
Incident record for E_INVALID_PROTOCOL_FORMAT
| Record | Purpose |
|---|---|
| First failing operation | API name, object state, and exact return point |
| Original representation | Unmodified bytes or a stable hash captured before repair or normalization |
| Contract identity | Schema, protocol, database, or persistence version with feature flags |
| Negative control | One intentionally invalid case that must remain rejected |
Repeatability versus recovery for E_INVALID_PROTOCOL_FORMAT
A retry that drops E_INVALID_PROTOCOL_FORMAT may reflect changed process state, cache contents, timing, or input; repeat the same test in a fresh process and after the correction to distinguish repair from a transient path change.
Opening handshake evidence for E_INVALID_PROTOCOL_FORMAT
| Boundary | Required evidence |
|---|---|
| Client request | Method, target, Host, Upgrade, Connection, key, version, protocols, and extensions |
| Server response | Status, Upgrade, Connection, accept value, selected protocol, and extensions |
| Windows API inputs | Arrays, counts, and selected indices passed before the return |
| Post-handshake actions | Action types, buffers, context tokens, and completion calls |
Deterministic protocol boundary for E_INVALID_PROTOCOL_FORMAT
Capture the first peer bytes or API transition yielding E_INVALID_PROTOCOL_FORMAT; backoff can limit a reconnect storm but cannot repair negotiation or state, and direct versus proxied tests may differ because an intermediary can terminate and recreate the WebSocket.
Regression sequence for E_INVALID_PROTOCOL_FORMAT
- Complete a baseline RFC 6455 handshake without optional extensions
- Exchange text and binary messages through the documented action loop
- Perform a clean close in both directions
- Introduce only the version, protocol, extension, frame, or call-order defect represented here
Wire and API ownership for E_INVALID_PROTOCOL_FORMAT
| Boundary | Responsibility |
|---|---|
| HTTP upgrade | Owns request and response header syntax before the session opens |
| WebSocket framing | Owns opcode, masking, reserved bits, length encoding, fragmentation, and control-frame rules |
| Negotiated feature | Owns extension or subprotocol selection and its parameters |
| Windows action loop | Owns local handle state, buffers, action completion, and close sequencing |
Technical references for E_INVALID_PROTOCOL_FORMAT
- Microsoft Open Specifications: HRESULT values
- Microsoft WebSocket handshake completion
- Microsoft WebSocket action queue API
- RFC 6455: The WebSocket Protocol
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