Transformation FoldConstants() raises ONNXRuntimeError

Using the transformation FoldConstants() from module finn.transformation.fold_constants raises an ONNXRuntimeError. The following script is run in a brand new FINNv0.3 docker container:

import onnx
import brevitas.onnx as bo
from finn.util.test import get_test_model_trained
from finn.core.modelwrapper import ModelWrapper
from finn.transformation.infer_shapes import InferShapes
from finn.transformation.fold_constants import FoldConstants

tfc = get_test_model_trained("TFC", 1, 1)
bo.export_finn_onnx(tfc, (1, 1, 28, 28), "./tfc_w1_a1.onnx")
model = ModelWrapper("./tfc_w1_a1.onnx")
model = model.transform(InferShapes())
model = model.transform(FoldConstants())

It raises the following error:

...
[ONNXRuntimeError] : 2 : INVALID_ARGUMENT : Failed to load model with error: Unknown model file format version.

Full error message can be found here: https://pastebin.com/kG3rsYf1

As a consequence, all notebooks running this transformation cannot be run (tfc_end2end_example, tfc_end2end_verification and cnv_end2end_example, 1_brevitas_network_import).

Testing the same piece of code in the docker container with the FINNv0.2.1b release raises no error.

[maltanar]

Actually I just saw that our Jenkins CI was failing due to this problem today, so decided to fix this quickly. 4436914f0a212584cbc36a6bae2381374031ff4b is now in both dev and master to address this. Can you confirm that the fix also works for you @QDucasse ?

[QDucasse]

This solved the issue!