Solved by ptrblck in post #3 
              
              
                Your model works fine with an input of [batch_size, 3, 128, 128]: 
model = AutoEncoder()
x = torch.randn(2, 3, 128, 128)
out = model(x)
print(out.shape)
> torch.Size([2, 3, 130, 130])

so I guess the shape of your model output doesn’t match the target shape. 
If that’s the case, you would have to ch…