keras-team/keras · error · ValueError

The number of input channels must match the kernel's input c

Error message

The number of input channels must match the kernel's input channels. Received: input channels={input_channels}, kernel input channels={kernel_input_channels}, data_format='{data_format}'.

What it means

Error "The number of input channels must match the kernel's input channels. Received: input channels={input_channels}, kernel input channels={kernel_input_channels}, data_format='{data_format}'." thrown in keras-team/keras.

Source

Thrown at keras/src/backend/common/backend_utils.py:392

    """Validate a conv input against its kernel shape.

    Used by `conv`, `depthwise_conv`, and `separable_conv` — all share the
    convention that the kernel's input-channel dimension is `kernel.shape[-2]`.
    Produces a clear error message before the backend op raises its own
    implementation-specific one.
    """
    input_channels = (
        inputs.shape[-1] if data_format == "channels_last" else inputs.shape[1]
    )
    kernel_input_channels = kernel.shape[-2]
    # Only validate when both dimensions are concrete Python ints. Dynamic
    # dimensions can come in forms other than `None` during tracing.
    if (
        isinstance(input_channels, int)
        and isinstance(kernel_input_channels, int)
        and input_channels != kernel_input_channels
    ):
        raise ValueError(
            "The number of input channels must match the kernel's input "
            f"channels. Received: input channels={input_channels}, kernel "
            f"input channels={kernel_input_channels}, "
            f"data_format='{data_format}'."
        )


def check_conv_transpose_input_channels(inputs, kernel, data_format):
    """Validate a conv_transpose input against its kernel shape.

    `conv_transpose` kernels use the layout
    `(spatial..., out_channels, in_channels)`, so the input-channel dimension
    is at `kernel.shape[-1]` (vs. `kernel.shape[-2]` for regular conv).
    """
    input_channels = (
        inputs.shape[-1] if data_format == "channels_last" else inputs.shape[1]
    )
    kernel_input_channels = kernel.shape[-1]

View on GitHub (pinned to 7a34a03db6)

When it happens

Trigger: Thrown at keras/src/backend/common/backend_utils.py:392 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of keras-team/keras@7a34a03db6 (2026-08-25). Data as JSON: /api/errors/f452c609a2508701. Report an issue: GitHub.