I am trying to export a custom model (VGG + LSTM) from pytorch to an Android phone. I am using pytorch 1.9 both on the laptop and the android device.
The exported model is optimized with this:
traced_model = torch.jit.trace(rnn_model, example_inputs=x_dummy)
traced_model = optimize_for_mobile(traced_model)

But when I run model.forward(…) on the android device I get the following error:
Pending exception com.facebook.jni.CppException: required rank 4 tensor to use channels_last format

Everything works fine without optimization. Any idea?