Concrt140.dll import error on Windows 10, no Anaconda


Recently, we’ve had trouble importing one of our in-house binary Python modules. It can be imported using the console python or ipython interpreters. In Jupyter notebook, or when running “nbconvert --execute”, import would fail with

The specified procedure could not be found

I went through the binary’s dependencies with Dependency Walker, importing each one in a Jupyter Notebook with ctypes.WinDLL. It turns out that concrt140.dll is the problematic dependency. It can be imported with running python -c "import ctypes; ctypes.WinDLL('concrt140.dll')", but the same fails on Jupyter Notebook.

We’re using Jupyter Notebook and nbconvert on Windows 10. We’re not using Anaconda, but stock Python 3.6.8 64bit. The problem I described can be reproduced in any fresh virtual environment on Windows 10.

I appreciate any help and ideas on what to try out!


I tracked it down to an issue with pyzmq: Windows 10 Conflict with concrt140.dll · Issue #1489 · zeromq/pyzmq · GitHub

The problem will be fixed in the next pyzmq release, version 22.