How to resolve this value error while loading saved model

I was doing semantic segmentation using Unet. When I tried to save the trained model and reload it with joblib but it is giving me this error.

model = build_unet((H, W, 3))
metrics = [dice_coef, iou, Recall(), Precision()]
model.compile(loss=dice_loss, optimizer=Adam(lr), metrics=metrics)

callbacks = [
    ModelCheckpoint(model_path, verbose=1, save_best_only=True),
    ReduceLROnPlateau(monitor='val_loss', factor=0.1, patience=5, min_lr=1e-7, verbose=1),
    CSVLogger(csv_path)
]

model.fit(
    train_dataset,
    epochs=num_epochs,
    validation_data=valid_dataset,
    callbacks=callbacks
)

joblib.dump(model, 'model_joblib')
loaded_model = joblib.load('model_joblib')