pypa/pip · error · ValueError

unexpected show-ref line

Error message

unexpected show-ref line: {line!r}

What it means

Raised by Git.get_revision_sha() when a line of 'git show-ref' output cannot be split into exactly two whitespace-separated parts (ref_sha and ref_name). This is an internal parsing error indicating the git command produced output in an unexpected format.

Solutions

1. Check your git version: 'git --version' — upgrade if significantly outdated
2. Run 'git show-ref <rev>' manually in the repo to inspect the output format
3. Clean the git repo state: 'git gc' or re-clone the repository
4. Report a pip bug with the git version and the show-ref output if it persists

Example fix

// before
pip install git+https://example.com/repo.git@some-ref
// after
# inspect the git output manually
cd /tmp/clone && git show-ref some-ref
git --version  # ensure a supported git version
# re-clone cleanly if the repo state is corrupt
pip install --force-reinstall git+https://example.com/repo.git@some-ref

def is_valid_show_ref_line(line: str) -> bool:
    parts = line.split(' ')
    return len(parts) == 2 and all(parts)

try:
    sha, is_branch = Git.get_revision_sha(dest, rev)
except ValueError as e:
    if 'unexpected show-ref line' in str(e):
        # inspect git version and output, report as environment issue
        logger.error('git show-ref output unexpected: %s', e)
        raise EnvironmentError(f'unsupported git version or corrupt repo: {e}')
    raise

When it happens

Trigger: Calling get_revision_sha(dest, rev) where the 'git show-ref <rev>' output contains a line that does not match the expected '<sha> <refname>' two-token format. The ValueError is raised at line 173 after a failed str.split with maxsplit=2.

Common situations: A git version that changes the show-ref output format (extremely rare). A corrupted or unusual git state. A ref name containing unusual characters. Essentially an unexpected internal state — this should not occur under normal git versions.

Related errors

• Badly formatted data
• Cannot find command - invalid PATH
• {url}
• Can't verify hashes for these requirements because we don't…
• Configuration file could not be loaded.\n

AI-assisted analysis of pypa/pip@f399c37189 (2026-08-08). Data as JSON: /api/errors/a7902a199e75dad0. Report an issue: GitHub.

Appendix: source

Thrown at src/pip/_internal/vcs/git.py:173

            cwd=dest,
            show_stdout=False,
            stdout_only=True,
            on_returncode="ignore",
        )
        refs = {}
        # NOTE: We do not use splitlines here since that would split on other
        #       unicode separators, which can be maliciously used to install a
        #       different revision.
        for line in output.strip().split("\n"):
            line = line.rstrip("\r")
            if not line:
                continue
            try:
                ref_sha, ref_name = line.split(" ", maxsplit=2)
            except ValueError:
                # Include the offending line to simplify troubleshooting if
                # this error ever occurs.
                raise ValueError(f"unexpected show-ref line: {line!r}")

            refs[ref_name] = ref_sha

        branch_ref = f"refs/remotes/origin/{rev}"
        tag_ref = f"refs/tags/{rev}"

        sha = refs.get(branch_ref)
        if sha is not None:
            return (sha, True)

        sha = refs.get(tag_ref)

        return (sha, False)

    @classmethod
    def _should_fetch(cls, dest: str, rev: str) -> bool:
        """
        Return true if rev is a ref or is a commit that we don't have locally.

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