Python "ImportError: libgthread-2.0.so.0: cannot open" in CI

A compiled package imported fine to pip but, at import time, needs the GLib threading runtime (libgthread-2.0.so.0) which is not installed on a minimal runner image.

What this error means

Importing a package such as opencv crashes with ImportError: libgthread-2.0.so.0: cannot open shared object file: No such file or directory. The wheel installed cleanly; only the system GLib library is missing.

ImportError: libgthread-2.0.so.0: cannot open shared object file:
No such file or directory

Common causes

GLib runtime not installed

Slim/headless images omit GLib. Wheels that dynamically link libgthread/libglib import fine on a full image but fail here.

Heavier package variant than needed

A GUI-enabled variant (e.g. opencv-python) pulls in GLib at import; a headless variant avoids it.

How to fix it

Install the GLib runtime

# Debian/Ubuntu
apt-get update && apt-get install -y libglib2.0-0

Use a headless variant where possible

pip uninstall -y opencv-python
pip install opencv-python-headless

How to prevent it

• Bake GLib (libglib2.0-0) into images that import such wheels.
• Prefer headless package variants in CI.
• Map each .so in an ImportError to its system package and install it in the image.

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