Error when checking target: expected dense_1 to have shape (257, 257) but got array with shape (257, 1)

问题

print(X.shape,Y.shape)
#(5877, 257, 1) (5877, 257, 1)
model = Sequential()
model.add(LSTM(257, input_shape=(257,1),stateful=False,return_sequences=True))
model.add(Dense(257, activation='sigmoid'))
model.compile(loss=losses.mean_squared_error, optimizer='adam', metrics=['accuracy'])
model.fit(x=X,y=Y,epochs=100,shuffle=False)

Error when checking target: expected dense_1 to have shape (257, 257) but got array with shape (257, 1)

I should give 5877 frames of size 257 to lstm layer. The output has the same format. Where I was mistaken?

来源：https://stackoverflow.com/questions/50858871/error-when-checking-target-expected-dense-1-to-have-shape-257-257-but-got-ar