aio-libs/aiohttp · error · HTTPBadRequest

Unsupported version: {version}

Error message

Unsupported version: {version}

What it means

Error "Unsupported version: {version}" thrown in aio-libs/aiohttp.

Source

Thrown at aiohttp/web_ws.py:311

            ]

            for proto in req_protocols:
                if proto in self._protocols:
                    protocol = proto
                    break
            else:
                # No overlap found: Return no protocol as per spec
                ws_logger.warning(
                    "%s: Client protocols %r don’t overlap server-known ones %r",
                    request.remote,
                    req_protocols,
                    self._protocols,
                )

        # check supported version
        version = headers.get(hdrs.SEC_WEBSOCKET_VERSION, "")
        if version not in ("13", "8", "7"):
            raise HTTPBadRequest(text=f"Unsupported version: {version}")

        # check client handshake for validity
        key = headers.get(hdrs.SEC_WEBSOCKET_KEY)
        try:
            if not key or len(base64.b64decode(key)) != 16:
                raise HTTPBadRequest(text=f"Handshake error: {key!r}")
        except binascii.Error:
            raise HTTPBadRequest(text=f"Handshake error: {key!r}") from None

        accept_val = base64.b64encode(
            hashlib.sha1(key.encode() + WS_KEY).digest()
        ).decode()
        response_headers = CIMultiDict(
            {
                hdrs.UPGRADE: "websocket",
                hdrs.CONNECTION: "upgrade",
                hdrs.SEC_WEBSOCKET_ACCEPT: accept_val,
            }

View on GitHub (pinned to c0ef574e29)

When it happens

Trigger: Thrown at aiohttp/web_ws.py:311 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of aio-libs/aiohttp@c0ef574e29 (2026-08-04). Data as JSON: /data/errors/c0094f0d3d238708.json. Report an issue: GitHub.