ImportError: libGL.so.1: cannot open shared object file: No such file or directory

How to fix ImportError: libGL.so.1: cannot open shared object file: No such file or directory

You are on a headless box and opencv-python wants GUI system libs. Two fixes: install the lib (sudo apt-get install libgl1, often plus libglib2.0-0), or switch to the headless wheel: pip install opencv-python-headless. The headless wheel is the right call for servers and Docker; it has no GUI deps at all.

The exact error

ImportError: libGL.so.1: cannot open shared object file: No such file or directory

Fix it

1. Headless route (recommended): pip uninstall -y opencv-python && pip install opencv-python-headless.

Expected: import cv2 works

1. Or install system libs: sudo apt-get install -y libgl1 libglib2.0-0.

Expected: import cv2 works with the GUI wheel

1. Docker: add the apt line to your Dockerfile before pip install.

Expected: container imports cv2 cleanly

When this applies

import cv2 fails on libGL.so.1 (or libgthread) in Docker/CI/headless Linux

When this does NOT apply

you actually need cv2.imshow (then install the libs, do not go headless)

Versions

Linux Docker / headless servers, opencv-python

Why it happens

opencv-python links Qt/OpenGL system libraries that slim images do not ship.

Edge cases

Never install both opencv-python and opencv-python-headless; they conflict.