lightingghost commented on issue #10220: Check failed: !ndinputs.back()->is_none() URL: https://github.com/apache/incubator-mxnet/issues/10220#issuecomment-386832157 It seem this error is related to the `FullyConnected` operator. The following code will reproduce the error: ```python x = nd.ones((3, 2)) y = nd.ones((2, 20)) y.attach_grad() z = g.Parameter('weight', shape=(20, 2)) z.initialize(ctx=mx.cpu()) with autograd.record(): #a = nd.dot(x, z.data(), transpose_b=True) a = nd.FullyConnected(x, z.data(), None, num_hidden=20, no_bias=True) a = a.reshape((-1, 4, 5)) b = nd.ones((3, 5, 6)) a = 0.5 <= a e = nd.batch_dot(a, b) f = e.sum() f.backward() ``` But changing `FullyConnected` to `dot` will be fine. Further dive into the `imperative.cc` shows the heap address of the output of `FullyConnected` was used to store the output of `reshape` and then `sum`, making the backward function unable to find the output of `FullyConnected`. As a workaround, I can write my own `Dense` block which use `dot` instead of `FullyConnected`, but I think this problem still worth investigation. Btw, why does `Dense` use `FullyConnected` instead of `dot` initially? Doing the multiplication and addition in a single operator? Another thing is, the `info` property in `NDArray` has type of `dmlc::any`, which is very hard to debug in `lldb`, is there a method you suggest that can see the content in `info`? Thanks
---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
