Hi, I encountered the same issue. For me, the solution was to make sure I was using Python 3.8 rather than a later version and ensuring that some Brightway-related packages matched the requirements from openlca2bw. Immediately after creating a new virtual environment and only installing openlca2bw via pip, for some reason the wrong package versions of bw2io and bw2parameters were installed.
So for me, the complete installation was:
(creating virtual environment)
pip install openlca2bw
pip install bw2io<0.8.9
pip install bw2parameters==0.6.6
After that, it worked for me :)
Best,
Maria