langchain-ai/deepagents · error · OSError

temporary artifact is not a regular file

Error message

temporary artifact is not a regular file

What it means

Raised by `_allocate_temp_artifact` after writing the temp file: `stat.S_ISREG(file_stat.st_mode)` is false, so the path returned by `tempfile.mkstemp` is not a regular file. The library verifies this defensively because a swapped `tempfile` module or a symlink/ATTACK on the temp directory could substitute a non-regular object (FIFO, socket, device).

Source

Thrown at libs/code/deepagents_code/auto_mode.py:1055

    *,
    thread_key: str,
    turn_id: str,
    tool_call_id: str,
) -> AutoTempArtifact:
    data = content.encode("utf-8")
    temp_root = Path(tempfile.gettempdir()).absolute()
    file_descriptor, raw_path = tempfile.mkstemp(
        prefix=_TEMP_ARTIFACT_PREFIX,
        suffix=suffix,
        dir=temp_root,
    )
    file_path = Path(raw_path)
    complete = False
    try:
        file_stat = _write_temp_artifact_bytes(file_descriptor, data)
        if not stat.S_ISREG(file_stat.st_mode):
            msg = "temporary artifact is not a regular file"
            raise OSError(msg)
        getuid = getattr(os, "getuid", None)
        if callable(getuid) and file_stat.st_uid != getuid():
            msg = "temporary artifact is not owned by this user"
            raise OSError(msg)
        if os.name != "nt" and stat.S_IMODE(file_stat.st_mode) & 0o077:
            msg = "temporary artifact permissions are too broad"
            raise OSError(msg)
        artifact = AutoTempArtifact(
            allocation_id=uuid4().hex,
            file_path=str(file_path),
            thread_key=thread_key,
            turn_id=turn_id,
            created_by_tool_call_id=tool_call_id,
            file_device=file_stat.st_dev,
            file_inode=file_stat.st_ino,
        )
        complete = True
        return artifact

View on GitHub (pinned to a1af029e6e)

Solutions

1. Verify the real stdlib `tempfile` is in use: `python -c "import tempfile; print(tempfile.__file__)"` — remove any shadowing `tempfile.py` or monkeypatch
2. Check that the temp directory (`tempfile.gettempdir()` / `$TMPDIR`) is on a normal filesystem that supports regular files
3. Inspect for security software or containers that substitute files in `/tmp` and switch to a different `TMPDIR`
4. If seen in tests, stop patching `tempfile.mkstemp` in a way that returns non-regular fd/path pairs

import tempfile, stat, os
real = getattr(tempfile, "__file__", "")
assert "stdlib" in real or real.startswith(os.path.dirname(os.__file__)), "tempfile is shadowed"
fd, p = tempfile.mkstemp(); st = os.fstat(fd); os.close(fd); os.unlink(p)
assert stat.S_ISREG(st.st_mode), "mkstemp did not yield a regular file"

try:
    artifact = create_temp_artifact(content=content, suffix="")
except OSError as exc:
    if "not a regular file" in str(exc):
        inspect_tempfile_module_and_tmpdir()
    else:
        raise

When it happens

Trigger: Calling `create_temp_artifact` (which calls `_allocate_temp_artifact`) when the `mkstemp` result lstats as a non-regular file — typically because `tempfile` was monkeypatched or shadowed, or the temp directory was replaced by something that hands back non-regular inodes.

Common situations: Test scaffolding or site-packages shadowing the stdlib `tempfile` module; unusual temp filesystems that report non-regular modes; security tooling that replaces temp files with FIFOs/devices to intercept writes.

Related errors

• temporary artifact is not owned by this user
• temporary artifact permissions are too broad
• temporary artifact provenance is invalid
• temporary artifact identity changed
• Permission path must not contain '..': {path!r}

AI-assisted analysis of langchain-ai/deepagents@a1af029e6e (2026-08-29). Data as JSON: /api/errors/c5264d9c1ae0000b. Report an issue: GitHub.