We currently do not support distribution strategy with a `Sequential` model

[wangxianzhe]

How should this problem be solved？

ValueError: We currently do not support distribution strategy with a Sequential model that is created without input_shape/input_dim set in its first layer or a subclassed model.

[arindas]

Relevant stackoverflow post:
https://stackoverflow.com/questions/56325408/input-shape-not-recognised-in-keras-model

Now the problem is, we don't use the Sequential class. I didn't find any invocation using grep.
Could you post a complete stacktrace here?