You didn't specify the shape of y which I think is the reason for this error. However, here is my point:

Tensorflow has two potential formats for target values (y) and the selection of the loss defines which is expected.

• SparseCategorialCrossentropy: expects the target to be an integer corresponding to the index. For example, if there are 10 potential target values, y would be between 0 and 9.

• CategoricalCrossEntropy: Expects the target value of an example to be one-hot encoded where the value at the target index is 1 while the other N-1 entries are zero. An example with 10 potential target values, where the target is 2 would be [0,0,1,0,0,0,0,0,0,0].