I am receiving and import error when trying to import cv2 in python (Ubuntu 18.04)

Question

First of all, thank you very much for reading.

Some days ago I installed Python3 (3.6.9) and opencv 3.4.10 in an Ubuntu 18.04 desktop system. I needed to downgrade opencv to 3.4.0 after some compilation problems (not related to python3), so I removed opencv 3.4.10 by using the sudo make uninstall order, and tested that it was uninstalled as if I tried importing it in python I got the following error:

libopencv_hfs.so.3.4: cannot open shared object file: no such file or directory

I thought installing 3.4.0 version would solve the problem but now that it's installed, when I try to import it in a python3 script I am getting the same error. I think this error must be related to the way python3 references the import files. I think it's still pointing to the uninstalled version of 3.4.10, but I can not find the way to change it.

Could someone please help me with this issue?

Thank you very much.

Andrés.

Answer 1

Using a virtualenv would resolve the issue. Check this out on how to use : Installing packages using pip and virtual environments

Once you're done installing requirements in the virtualenv, run your python script there only to use the specified versions.

Answer 2

Hello again and thank you for you answers.

I have been able to solve the problem. Thought I had uninstalled the previous version of opencv, there was still a cv2.so file in my python virtual environment path, and it had not been replaced by the new cv2.so , so python tried to import the old one instead of the new one.

The old cv2.so (the one that was referenced when I imported cv2 in python) was here --> ~/.virtualenvs/cv/lib/python3.6/site-packages/cv2.so The cv2.so I wanted to be used when imported was here --> /usr/local/lib/python3.6/site-packages/cv2/cv2.so so I replaced the one in the virtual environment path with the one in the lib directory and that did the trick :)