pypa/pip · error · Exception

No input was expected ($PIP_NO_INPUT set); question

Error message

No input was expected ($PIP_NO_INPUT set); question: {message}

What it means

Raised as a generic Exception by _check_no_input (misc.py:253) when the PIP_NO_INPUT environment variable is set and pip needs to ask the user an interactive question (confirmation prompt, choice selection, or password). Setting PIP_NO_INPUT (equivalent to --no-input) tells pip to never prompt for input; if it reaches a code path that requires input, it fails immediately rather than hanging on a blocked stdin. This is essential for non-interactive CI/automation.

Solutions

Set PIP_EXISTS_ACTION=a (or the relevant action letters) to auto-answer file-exists prompts without interaction.
Provide credentials via environment variables (PIP_INDEX_USER, PIP_INDEX_PASSWORD), a keyring, or a netrc file instead of interactive prompts.
Remove PIP_NO_INPUT if you actually want interactive prompts.
Pre-resolve the condition causing the prompt (e.g. clean the target directory, pin versions to avoid conflicts).

Example fix

// before
export PIP_NO_INPUT=1
pip install pkg  # hits overwrite confirmation

// after
export PIP_NO_INPUT=1
export PIP_EXISTS_ACTION=a
pip install pkg

Defensive patterns

Strategy: validation

Validate before calling

import os

def ensure_no_prompt_conflicts():
    """Set PIP_EXISTS_ACTION and credentials before PIP_NO_INPUT to avoid prompts."""
    if os.environ.get('PIP_NO_INPUT'):
        os.environ.setdefault('PIP_EXISTS_ACTION', 'a')  # auto-overwrite
        if not (os.environ.get('PIP_INDEX_USER') or os.path.get('PIP_INDEX_URL')):
            print('Warning: PIP_NO_INPUT set but no non-interactive credentials configured.')

Prevention

Always pair PIP_NO_INPUT=1 with PIP_EXISTS_ACTION to handle overwrite prompts.
Provide index credentials via env vars or netrc rather than interactive prompts.
Test pip commands in CI before deploying to ensure no hidden prompt triggers.

When it happens

Trigger: PIP_NO_INPUT=1 is set (or --no-input passed) and pip encounters a situation requiring a prompt: ask(), ask_path_exists(), ask_input(), or ask_password() all call _check_no_input first (lines 261, 275, 281). Examples: a file-exists confirmation, a keyring/Git credential prompt, or a dependency conflict that needs a user decision.

Common situations: CI pipelines with PIP_NO_INPUT=1 where pip needs confirmation for an overwrite (PIP_EXISTS_ACTION not set). Docker builds with --no-input that encounter a package needing credential input for a private index. Automation scripts that set PIP_NO_INPUT globally and hit an unexpected prompt.

Related errors

AI-assisted analysis of pypa/pip@f399c37189 (2026-08-08). Data as JSON: /api/errors/dc611c7f51ce114f. Report an issue: GitHub.

Appendix: source

Thrown at src/pip/_internal/utils/misc.py:253

    n = 1
    extension = ext
    while os.path.exists(dir + extension):
        n += 1
        extension = ext + str(n)
    return dir + extension


def ask_path_exists(message: str, options: Iterable[str]) -> str:
    for action in os.environ.get("PIP_EXISTS_ACTION", "").split():
        if action in options:
            return action
    return ask(message, options)


def _check_no_input(message: str) -> None:
    """Raise an error if no input is allowed."""
    if os.environ.get("PIP_NO_INPUT"):
        raise Exception(
            f"No input was expected ($PIP_NO_INPUT set); question: {message}"
        )


def ask(message: str, options: Iterable[str]) -> str:
    """Ask the message interactively, with the given possible responses"""
    while 1:
        _check_no_input(message)
        response = input(message)
        response = response.strip().lower()
        if response not in options:
            print(
                "Your response ({!r}) was not one of the expected responses: "
                "{}".format(response, ", ".join(options))
            )
        else:
            return response

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