# About libtorch "model.to(device)"

**URL:** <https://discuss.pytorch.org/t/about-libtorch-model-to-device/147595>\
**Category:** C++\
**Created:** [March 28, 2022, 6:53am UTC](https://discuss.pytorch.org/t/about-libtorch-model-to-device/147595 "2022-03-28T06:53:39Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![salt0107fish](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/salt0107fish/32/48010_2.png) [@salt0107fish](https://discuss.pytorch.org/u/salt0107fish)\
**Post date:** [March 28, 2022, 6:53am UTC](https://discuss.pytorch.org/t/about-libtorch-model-to-device/147595/1 "2022-03-28T06:53:39Z")

</div>

Hi, I got a question when I Debug my c++ code.  
The code is just like following:

```auto
torch::DeviceType device_type;
device_type = torch::kCUDA;
torch::Device device(device_type);
…………
auto img_var = torch::from_blob(mRGB.data, dims, torch::kFloat32).to(device);
…………
modle_vlad.to(device);
modle_vlad.eval();

```

And the error is about “modle\_vlad.to(device);”

```auto
  what(): _ivalue_ INTERNAL ASSERT FAILED at "../torch/csrc/jit/api/object.cpp":19, please report a bug to PyTorch. 
Exception raised from _ivalue at ../torch/csrc/jit/api/object.cpp:19 (most recent call first):
frame #0: c10::Error::Error(c10::SourceLocation, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) + 0x69 (0x7fff074b9b29 in /usr/local/libtorch1.8.2/libtorch/lib/libc10.so)
frame #1: torch::jit::Object::_ivalue() const + 0x2c8 (0x7fff8435dc38 in /usr/local/libtorch1.8.2/libtorch/lib/libtorch_cpu.so)
frame #2: <unknown function> + 0x3484f38 (0x7fff8435cf38 in /usr/local/libtorch1.8.2/libtorch/lib/libtorch_cpu.so)
frame #3: torch::jit::Module::to_impl(c10::optional<c10::Device> const&, c10::optional<c10::ScalarType> const&, bool) + 0x15a (0x7fff8434d28a in /usr/local/libtorch1.8.2/libtorch/lib/libtorch_cpu.so)
frame #4: torch::jit::Module::to(c10::Device, bool) + 0x37 (0x7fff8434e377 in /usr/local/libtorch1.8.2/libtorch/lib/libtorch_cpu.so)
…………

```

It is strange that I have no difficulty to transform the cv::Mat to GPU tensor , but it shows that some errors ocurr when I try to transform my model to GPU. I used the same code to transform other model to GPU a few days before, and it had no problem.  
Could you please help me with the question?

---

<div class="post-metadata">

**Author:** ![ptrblck](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/ptrblck/32/1823_2.png) [@ptrblck](https://discuss.pytorch.org/u/ptrblck)\
**Post date:** [March 28, 2022, 7:09am UTC](https://discuss.pytorch.org/t/about-libtorch-model-to-device/147595/2 "2022-03-28T07:09:05Z")

</div>

In case you are seeing this error using the latest release, could you please create an issue on [GitHub](https://github.com/pytorch/pytorch/issues) with a minimal, executable code snippet to reproduce the issue, please?