huggingface/transformers · error · KeyError

Key {key} is not a valid field of SizeDict.

Error message

Key {key} is not a valid field of SizeDict.

What it means

Error "Key {key} is not a valid field of SizeDict." thrown in huggingface/transformers.

Source

Thrown at src/transformers/image_utils.py:1050

            return getattr(self, key)
        return default

    def __iter__(self):
        # Yield only non-None (key, value) pairs so dict(self) excludes missing values.
        for f in fields(self):
            val = getattr(self, f.name)
            if val is not None:
                yield f.name, val

    def __hash__(self):
        return hash((self.height, self.width, self.longest_edge, self.shortest_edge, self.max_height, self.max_width))

    def __contains__(self, key):
        return hasattr(self, key) and getattr(self, key) is not None

    def __setitem__(self, key, value):
        if not hasattr(self, key):
            raise KeyError(f"Key {key} is not a valid field of SizeDict.")
        object.__setattr__(self, key, value)

    def __eq__(self, other):
        if isinstance(other, dict):
            return dict(self) == other
        if isinstance(other, SizeDict):
            return tuple(getattr(self, f.name) for f in fields(self)) == tuple(
                getattr(other, f.name) for f in fields(self)
            )
        return NotImplemented

    def __or__(self, other) -> "SizeDict":
        if isinstance(other, dict | SizeDict):
            merged = dict(self)
            merged.update(dict(other))
            return SizeDict(**merged)
        return NotImplemented

View on GitHub (pinned to a597f97485)

Solutions

1. Set only valid SizeDict fields such as 'height', 'width', 'shortest_edge', 'longest_edge', 'max_height', 'max_width'.

When it happens

Trigger: Raised in SizeDict assignment when attempting to set a key that is not a declared field.

Common situations: Assigning arbitrary attributes to a SizeDict instead of its allowed size-related fields.

AI-assisted analysis of huggingface/transformers@a597f97485 (2026-08-14). Data as JSON: /api/errors/fa56a597ea331ba2. Report an issue: GitHub.