error: externally-managed-environment
ERROR: Could not install packages due to an OSError: [Errno 13] Permission denied
ERROR: No matching distribution found for package==1.0

pip install can fail for many reasons. Here are the most common ones.

Fix 1: Externally Managed Environment

# ❌ System Python is protected (Ubuntu 23.04+, Fedora 38+)
pip install requests  # 💥 externally-managed-environment

# ✅ Use a virtual environment
python3 -m venv venv
source venv/bin/activate
pip install requests

Fix 2: Permission Denied

# ❌ Don't use sudo pip
sudo pip install requests  # Bad practice

# ✅ Use --user flag
pip install --user requests

# ✅ Or better: use a virtual environment
python3 -m venv venv
source venv/bin/activate
pip install requests

Fix 3: No Matching Distribution

# ❌ Package doesn't exist or wrong Python version
pip install nonexistent-package

# ✅ Check the correct package name on PyPI
pip install Pillow  # Not "pillow" or "PIL"

# Check your Python version
python3 --version
# Some packages don't support all Python versions

Fix 4: Version Conflict

# ❌ Two packages need different versions of a dependency
pip install package-a package-b  # 💥 Conflict

# ✅ Check what's conflicting
pip check

# ✅ Try installing with --upgrade
pip install --upgrade package-a package-b

Fix 5: SSL Certificate Error

# ❌ Corporate proxy or outdated certificates
pip install requests  # 💥 SSL: CERTIFICATE_VERIFY_FAILED

# ✅ Upgrade pip and certifi
pip install --upgrade pip certifi

# ✅ Temporary workaround (not recommended)
pip install --trusted-host pypi.org --trusted-host files.pythonhosted.org requests

Fix 6: Slow or Timeout

# ❌ PyPI is slow or blocked
pip install requests  # 💥 Timeout

# ✅ Use a mirror
pip install -i https://pypi.tuna.tsinghua.edu.cn/simple requests

# ✅ Increase timeout
pip install --timeout 120 requests

Related resources

• pip externally managed fix
• Python ModuleNotFoundError fix
• pip cheat sheet Related: Python AssertionError — How to Fix It