TorchScript compatibility between pytorch versions

jit
1

Hi,

I am trying to use libtorch in a C++ application that’s restricted to the gcc-4.8 ABI, which forces me to link against libtorch-1.2.0 (I was told newer version of libtorch aren’t compatible with that ABI).

This application needs to load a pre-trained model. That model was trained and saved from a python script that needs to use pytorch-1.3.0 or newer.

Trying to load the serialized TorchScript model aborts the program with this error:

terminate called after throwing an instance of 'c10::Error'
  what():  [enforce fail at inline_container.cc:137] . PytorchStreamReader failed closing reader: file not found

This happens both from the C++ and the python API. Is this a compatibility issue?

This is easily reproducible: from an environment with either pytorch-1.3.1 or 1.5.0, run

import torch

class TestModule(torch.nn.Module):
    def __init__(self, N, M):
        super().__init__()
        self.weight = torch.nn.Parameter(torch.rand(N, M))

    def forward(self, x):
        return self.weight.mv(x)

my_module = TestModule(10,20)
test_module = torch.jit.script(my_module)

test_module.save("test_module.pt")

Then from an environment with pytorch-1.2.0:

import torch
m = torch.jit.load('test_module.pt')

If the file was written from 1.5.0, I get

RuntimeError: version_number <= kMaxSupportedFileFormatVersion INTERNAL ASSERT FAILED at ../caffe2/serialize/inline_container.cc:131, please report a bug to PyTorch. Attempted to read a PyTorch file with version 2, but the maximum supported version for reading is 1. Your PyTorch installation may be too old.

which is clearly a compatibility issue. But if the file was written from 1.3.1, I get the “file not found” error above (note this is a process abort, not an exception, from both C++ and python API).

I could not find documentation on TorchScript file compatibility across versions. Is that information available somewhere?

Thanks,
A.

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2

Hi, we maintain backwards compatibility but not forwards compatiblity. New versions will work with older models, but older versions will not work with newer models.

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