Ubuntu 20.04重装Python3后出现ModuleNotFoundError问题求助

API 探路者

2026-4-23

Hey Bilal, sorry to hear you're stuck with this frustrating error after reinstalling Python 3 on Ubuntu 20.04. Let's walk through some targeted fixes that should resolve the ModuleNotFoundError for softwareproperties.SoftwareProperties:

Check your system's default Python 3 symlink
Ubuntu 20.04 relies on Python 3.8 as its default system Python, and mismatched symlinks are a common culprit here. First, verify where python3 points:
ls -l /usr/bin/python3
If it doesn't link to /usr/bin/python3.8, fix it with these commands:
sudo rm /usr/bin/python3
sudo ln -s /usr/bin/python3.8 /usr/bin/python3
Fully reinstall software-properties-common
A simple reinstall might not clear corrupted files—try purging the package completely first:
sudo apt purge --auto-remove software-properties-common
sudo apt update
sudo apt install software-properties-common
Verify Python can access the softwareproperties module
The module lives in /usr/lib/python3/dist-packages, so check if this path is in Python's system path. Run python3 in your terminal and enter:
import sys; print(sys.path)
If /usr/lib/python3/dist-packages isn't listed, ensure the directory has correct permissions:
sudo chmod -R 755 /usr/lib/python3/dist-packages
You can also try re-registering the module via pip (though it's typically managed by apt):
sudo python3 -m pip install --upgrade pip
sudo python3 -m pip install software-properties-common
Fix the add-apt-repository script's shebang line
Sometimes the script points to the wrong Python version. Open it with a text editor:
sudo nano /usr/bin/add-apt-repository
Check the first line—it should be either #!/usr/bin/python3 or #!/usr/bin/python3.8. If it's incorrect, modify it, save with Ctrl+O, then exit with Ctrl+X.
Reinstall core system Python packages
If none of the above works, restore the minimal system Python components:
sudo apt install --reinstall python3-minimal python3.8-minimal