FoundationAgents/OpenManus · error · RuntimeError

Failed to read file: {e}

Error message

Failed to read file: {e}

What it means

Catch-all RuntimeError from DockerSandbox.read_file (app/sandbox/core/sandbox.py:196): the archive was fetched but processing failed — decoding the tar stream, reading members, or content.decode("utf-8"). NotFound is handled separately (error 28); everything else (UnicodeDecodeError, tar errors, Docker API errors mid-stream) lands here with the cause in {e}.

Source

Thrown at app/sandbox/core/sandbox.py:196

        """
        if not self.container:
            raise RuntimeError("Sandbox not initialized")

        try:
            # Get file archive
            resolved_path = self._safe_resolve_path(path)
            tar_stream, _ = await asyncio.to_thread(
                self.container.get_archive, resolved_path
            )

            # Read file content from tar stream
            content = await self._read_from_tar(tar_stream)
            return content.decode("utf-8")

        except NotFound:
            raise FileNotFoundError(f"File not found: {path}")
        except Exception as e:
            raise RuntimeError(f"Failed to read file: {e}")

    async def write_file(self, path: str, content: str) -> None:
        """Writes content to a file in the container.

        Args:
            path: Target path.
            content: File content.

        Raises:
            RuntimeError: If write operation fails.
        """
        if not self.container:
            raise RuntimeError("Sandbox not initialized")

        try:
            resolved_path = self._safe_resolve_path(path)
            parent_dir = os.path.dirname(resolved_path)

View on GitHub (pinned to 52a13f2a57)

Solutions

1. Check {e}: UnicodeDecodeError means binary content — use copy_from instead of read_file for non-text files.
2. For directories or large files, use copy_from(src, dst) which handles tar extraction properly.
3. Retry once on connection-reset style errors (transient daemon/stream issues).
4. Confirm the path points at a regular file: run_command(f"test -f {path}").

Example fix

# before
text = await sandbox.read_file("chart.png")  # UnicodeDecodeError -> RuntimeError

# after
await sandbox.copy_from("chart.png", "/tmp/host/chart.png")  # binary-safe path

is_text = (await sandbox.run_command(f"file -b {shlex.quote(path)}")).strip().startswith("ASCII")

try:
    return await sandbox.read_file(path)
except RuntimeError as e:
    if "UnicodeDecodeError" in str(e.__cause__ or e):
        tmp = tempfile.mkdtemp()
        await sandbox.copy_from(path, tmp)
        return open(os.path.join(tmp, os.path.basename(path)), "rb").read()  # bytes path
    raise

When it happens

Trigger: Reading a binary file (PNG, pickle, zip) — content.decode("utf-8") raises UnicodeDecodeError; tar stream truncated mid-transfer; get_archive returning a directory when a file was expected; Docker API connection reset while streaming chunks.

Common situations: Agent writes a plot/screenshot then read_file is used on it; reading large files that hit daemon stream limits; reading a path that is a directory (archive has multiple members and the reader takes raw bytes).

Related errors

• Failed to write file: {e}
• Source file is empty: {src_path}
• Failed to copy file: {e}
• Failed to create sandbox: {e}
• File not found: {path}

AI-assisted analysis of FoundationAgents/OpenManus@52a13f2a57 (2026-08-15). Data as JSON: /api/errors/e1818096f1e71504. Report an issue: GitHub.