matplotlib/matplotlib · error · ValueError

Invalid hex color specifier: {orig_c!r}

Error message

Invalid hex color specifier: {orig_c!r}

What it means

Error "Invalid hex color specifier: {orig_c!r}" thrown in matplotlib/matplotlib.

Source

Thrown at lib/matplotlib/colors.py:409

        if re.fullmatch("#[a-fA-F0-9]+", c):
            if len(c) == 7:  # #rrggbb hex format.
                return (*[n / 0xff for n in bytes.fromhex(c[1:])],
                        alpha if alpha is not None else 1.)
            elif len(c) == 4:  # #rgb hex format, shorthand for #rrggbb.
                return (*[int(n, 16) / 0xf for n in c[1:]],
                        alpha if alpha is not None else 1.)
            elif len(c) == 9:  # #rrggbbaa hex format.
                color = [n / 0xff for n in bytes.fromhex(c[1:])]
                if alpha is not None:
                    color[-1] = alpha
                return tuple(color)
            elif len(c) == 5:  # #rgba hex format, shorthand for #rrggbbaa.
                color = [int(n, 16) / 0xf for n in c[1:]]
                if alpha is not None:
                    color[-1] = alpha
                return tuple(color)
            else:
                raise ValueError(f"Invalid hex color specifier: {orig_c!r}")
        # string gray.
        try:
            c = float(c)
        except ValueError:
            pass
        else:
            if not (0 <= c <= 1):
                raise ValueError(
                    f"Invalid string grayscale value {orig_c!r}. "
                    f"Value must be within 0-1 range")
            return c, c, c, alpha if alpha is not None else 1.
        raise ValueError(f"Invalid RGBA argument: {orig_c!r}")
    # turn 2-D array into 1-D array
    if isinstance(c, np.ndarray):
        if c.ndim == 2 and c.shape[0] == 1:
            c = c.reshape(-1)
    # tuple color.
    if not np.iterable(c):

View on GitHub (pinned to b379c1b69e)

When it happens

Trigger: Thrown at lib/matplotlib/colors.py:409 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of matplotlib/matplotlib@b379c1b69e (2026-08-21). Data as JSON: /api/errors/bdb784b57d307b00. Report an issue: GitHub.