mitmproxy/mitmproxy · error · ValueError

Bad HTTP response line: {line!r}

Error message

Bad HTTP response line: {line!r}

What it means

Error "Bad HTTP response line: {line!r}" thrown in mitmproxy/mitmproxy.

Source

Thrown at mitmproxy/net/http/http1/read.py:214

        raise_if_http_version_unknown(http_version)
    except ValueError as e:
        raise ValueError(f"Bad HTTP request line: {line!r}") from e

    return host, port, method, scheme, authority, path, http_version


def _read_response_line(line: bytes) -> tuple[bytes, int, bytes]:
    try:
        parts = line.split(None, 2)
        if len(parts) == 2:  # handle missing message gracefully
            parts.append(b"")

        http_version, status_code_str, reason = parts
        status_code = int(status_code_str)
        raise_if_http_version_unknown(http_version)
    except ValueError as e:
        raise ValueError(f"Bad HTTP response line: {line!r}") from e

    return http_version, status_code, reason


def _read_headers(lines: Iterable[bytes]) -> Headers:
    """
    Read a set of headers.
    Stop once a blank line is reached.

    Returns:
        A headers object

    Raises:
        exceptions.HttpSyntaxException
    """
    ret: list[tuple[bytes, bytes]] = []
    for line in lines:
        if line[0] in b" \t":

View on GitHub (pinned to 2ac5b089d9)

When it happens

Trigger: Thrown at mitmproxy/net/http/http1/read.py:214 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of mitmproxy/mitmproxy@2ac5b089d9 (2026-08-26). Data as JSON: /api/errors/fb139eb9e25ad2e8. Report an issue: GitHub.