keras-team/keras · error · ValueError

`cond` function must return a scalar boolean value, but got

Error message

`cond` function must return a scalar boolean value, but got shape {}

What it means

Error "`cond` function must return a scalar boolean value, but got shape {}" thrown in keras-team/keras.

Source

Thrown at keras/src/backend/openvino/core.py:1750

    param_tensors = [OpenVINOKerasTensor(p.output(0)) for p in params]

    packed_args, _ = pack_structure(loop_vars, param_tensors)
    if isinstance(packed_args, dict):
        body_out = body(packed_args)
    else:
        body_out = body(*packed_args)

    if not isinstance(body_out, (list, tuple, dict)):
        body_out = (body_out,)

    flat_body_out = flatten_structure(body_out)
    if isinstance(packed_args, dict):
        cond_output = get_ov_output(cond(body_out))
    else:
        cond_output = get_ov_output(cond(*body_out))

    if len(cond_output.get_partial_shape()) != 0:
        raise ValueError(
            "`cond` function must return a scalar boolean value, "
            "but got shape {}".format(cond_output.get_partial_shape())
        )

    for p, out in zip(params, flat_body_out):
        out_shape = get_ov_output(out).get_partial_shape()
        p.set_partial_shape(out_shape)

    results = [cond_output] + [get_ov_output(x) for x in flat_body_out]
    body_func = Model(results=results, parameters=params)
    loop.set_function(body_func)
    loop.set_special_body_ports([-1, 0])

    for param, init_val, next_val in zip(params, loop_vars_ov, flat_body_out):
        loop.set_merged_input(param, init_val, get_ov_output(next_val))

    outputs_flat = [
        OpenVINOKerasTensor(loop.get_iter_value(get_ov_output(val)))

View on GitHub (pinned to 7a34a03db6)

When it happens

Trigger: Thrown at keras/src/backend/openvino/core.py:1750 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/0aad586e5960dbb2. Report an issue: GitHub.