handle when a List is used as validation_data instead of a Tuple, in model.fit()
@@ -1564,6 +1564,8 @@ def unpack_x_y_sample_weight(data):
The unpacked tuple, with `None`s for `y` and `sample_weight` if they are not
provided.
"""
+ if isinstance(data, list):
+ data = tuple(data)
if not isinstance(data, tuple):
return (data, None, None)
elif len(data) == 1:
