Unable to load trace after VI

Questions
15

I also encounter the same problem. I try running the code on
https://docs.pymc.io/en/stable/pymc-examples/examples/variational_inference/bayesian_neural_network_advi.html

then do
pm.save_trace(trace, ‘test_trace’)
pm.load_trace(directory=‘test_trace’, model=neural_network)

results in the following error while pm.load_trace
TypeError: ‘NoneType’ object is not iterable

I tried on Colab, my local machine and AWS, all resulting in the same error.