error: externally-managed-environment

What you see

python -m pip install requests

error: externally-managed-environment

× This environment is externally managed
╰─> This Python installation is managed by uv and should not be modified.

note: If you believe this is a mistake, please contact your Python installation or OS distribution provider. You can override this, at the risk of breaking your Python installation or OS, by passing --break-system-packages.
hint: See PEP 668 for the detailed specification.

What it means

Your Python is marked as externally managed: something other than pip looks after its packages, and pip refuses to install into it outside a virtual environment. The marker is a file called EXTERNALLY-MANAGED in the interpreter's standard library folder. The rule comes from PEP 668.

The point is to stop pip and the system package manager from overwriting each other's files. On Debian or Ubuntu, apt owns the system Python; with Homebrew, brew does. A pip install there can break tools of the operating system that depend on exact versions.

The text inside the box comes from whoever ships your Python, so it differs. The example above ran on uv's managed builds, which ship the marker too; Homebrew and Debian print their own advice in the same frame.

Why it happens

• You are not in a virtual environment. Inside one, the marker does not apply.
• Your Python comes from a package manager that marks it, such as Homebrew, recent Debian and Ubuntu releases, or uv.
• A tutorial told you to run pip install globally. Many were written before distributions adopted the marker.

How to fix it

Make a virtual environment for the project and install there. This is what the error is asking for:

python3 -m venv .venv
source .venv/bin/activate
python -m pip install requests

For a command-line tool that you want everywhere, such as black or httpie, install it in its own environment with pipx install black or uv tool install black.

For a library the operating system packages itself, install the system package, for example sudo apt install python3-requests.

--break-system-packages makes pip install anyway. The name is accurate: use it only in a throwaway container, never on a machine you keep.

Example: --user is refused too

python -m pip install --user requests

error: externally-managed-environment

× This environment is externally managed
╰─> This Python installation is managed by uv and should not be modified.

note: If you believe this is a mistake, please contact your Python installation or OS distribution provider. You can override this, at the risk of breaking your Python installation or OS, by passing --break-system-packages.
hint: See PEP 668 for the detailed specification.

Run on CPython 3.12.15, 3.13.17, 3.14.9 and 3.15.1, on October 25, 2026.

How each Python version words it

Run on CPython 3.12.15, 3.13.17, 3.14.9 and 3.15.1, on October 25, 2026.

pip checks for the marker, not Python. Python itself has not changed here; what changed is which builds carry the marker. The runs above used pip 26.2.2, the version each of uv's builds bundles.