langchain-ai/deepagents · error · ChannelMediaError

media file type {detected!r} does not match requested type {

Error message

media file type {detected!r} does not match requested type {media.media_type!r}

What it means

`validate_media` sniffs the file's actual content type with `_media_type` (mimetypes-based detection) and compares it to the `media_type` requested on the `ChannelMedia`. A mismatch raises `ChannelMediaError`, guarding against sending mislabeled attachments that a channel would caption or process incorrectly.

Source

Thrown at libs/talon/deepagents_talon/channels/base.py:271

        ChannelMediaError: If the file is missing, unsupported, or too large.
    """
    try:
        path = (
            resolve_bounded_media_path(media.path, root, require_relative=False)
            if root is not None
            else media.path.expanduser()
        )
    except ValueError as exc:
        msg = str(exc)
        raise ChannelMediaError(msg) from exc
    if not path.is_file():
        msg = f"media file does not exist: {path}"
        raise ChannelMediaError(msg)

    detected = _media_type(path)
    if detected != media.media_type:
        msg = f"media file type {detected!r} does not match requested type {media.media_type!r}"
        raise ChannelMediaError(msg)

    return _validate_media_size(media, path=path, max_bytes=max_bytes)


def message_with_media_paths(
    message: ChannelMessage,
    *,
    media_paths: Sequence[str],
    mime_types: Sequence[str] = (),
    has_media: bool | None = None,
) -> ChannelMessage:
    """Return `message` with normalized inbound-media path metadata.

    Args:
        message: Original channel message.
        media_paths: Local media paths associated with the message.
        mime_types: MIME types aligned with `media_paths`.
        has_media: Optional provider-reported media presence. When omitted, this

View on GitHub (pinned to a1af029e6e)

Solutions

1. Set `media_type` to match the actual file, or fix the file's extension so detection matches.
2. Inspect the detected type in the error message and correct the `ChannelMedia` construction.
3. Catch `ChannelMediaError` and surface the mismatch to the caller.

Example fix

# before
ChannelMedia(path=Path('report.pdf'), media_type='image')

# after
ChannelMedia(path=Path('report.pdf'), media_type='document')

from deepagents_talon.channels.base import _media_type
path = Path(media.path)
if _media_type(path) != media.media_type:
    raise ValueError(f'{path} is {_media_type(path)}, not {media.media_type}')

try:
    await channel.send_media(media)
except ChannelMediaError as exc:
    if 'does not match requested type' in str(exc):
        await channel.send_text(f'Attachment type mismatch: {exc}')
    else:
        raise

When it happens

Trigger: Calling `validate_media`/`send_media` where `media.media_type` (e.g. 'image') does not match the type detected from the file extension/content (e.g. the file is actually a PDF or the extension is wrong).

Common situations: Renaming a file to `.png` when it is a JPEG is fine, but labeling a text file as 'image'; hardcoding `media_type='voice'` for a video; generated artifacts written with a generic extension like `.bin`.

Related errors

• Goal criteria request field {key} must be text.
• media file is too large: {size} bytes exceeds {max_bytes}
• {media.media_type} media is too large: {size} bytes exceeds
• unsupported media file type: {path}
• unsupported media mime type: {mime}

AI-assisted analysis of langchain-ai/deepagents@a1af029e6e (2026-08-29). Data as JSON: /api/errors/8fb6a56cf7f4366c. Report an issue: GitHub.