Keras Model Doesn't Learn At All

My model weights (I output them to weights_before.txt and weights_after.txt) are precisely the same before and after the training, i.e. the training doesn't change anything, there'

Solution 1:

The problem is that you are using softmax as the activation function of last layer. Essentially, softmax normalizes its input to make the sum of the elements to be one. Therefore, if you use it on a layer with only one unit (i.e. Dense(1,...)), then it would always output 1. To fix this, change the activation function of last layer to sigmoid which outputs a value in the range (0,1).