microsoft/autogen · error · ConnectionError

Error while downloading files

Error message

Error while downloading files

What it means

Raised by AzureContainerCodeExecutor.download_files when the GET to `files/content/{file}` returns an error HTTP status (ClientResponseError re-wrapped as ConnectionError). It occurs after the existence check passed, so it usually indicates an auth or transport problem rather than a missing file.

Source

Thrown at python/packages/autogen-ext/src/autogen_ext/code_executors/azure/_azure_container_code_executor.py:390

                        headers=headers,
                    )
                )
                cancellation_token.link_future(task)
                try:
                    resp = await task
                    resp.raise_for_status()
                    local_path = self.work_dir / file
                    local_paths.append(str(local_path))
                    async with await open_file(local_path, "wb") as f:
                        await f.write(await resp.read())
                except asyncio.TimeoutError as e:
                    # e.add_note is only in py 3.11+
                    raise asyncio.TimeoutError("Timeout downloading files") from e
                except asyncio.CancelledError as e:
                    # e.add_note is only in py 3.11+
                    raise asyncio.CancelledError("Downloading files cancelled") from e
                except aiohttp.ClientResponseError as e:
                    raise ConnectionError("Error while downloading files") from e
        return local_paths

    async def execute_code_blocks(
        self, code_blocks: List[CodeBlock], cancellation_token: CancellationToken
    ) -> CodeResult:
        """(Experimental) Execute the code blocks and return the result.

        Args:
            code_blocks (List[CodeBlock]): The code blocks to execute.
            cancellation_token (CancellationToken): a token to cancel the operation
            input_files (Optional[Union[Path, str]]): Any files the code blocks will need to access

        Returns:
            CodeResult: The result of the code execution."""

        self._ensure_access_token()
        if self._available_packages is None:
            await self._populate_available_packages(cancellation_token)

View on GitHub (pinned to 027ecf0a37)

Solutions

  1. Inspect e.__cause__ for the HTTP status to distinguish auth (401/403) from transport issues
  2. Call restart() and re-run/re-download when the session was lost (note: restart clears remote files, so the producing code must re-run)
  3. Retry the download call: files remain on the service, so a retry after a transient failure succeeds
  4. Batch downloads smaller or persist artifacts elsewhere if files are very large
Defensive patterns

Strategy: retry

Validate before calling

null

Type guard

null

Try / catch

try:
    paths = await executor.download_files(files, ct)
except ConnectionError:
    await asyncio.sleep(1)
    paths = await executor.download_files(files, ct)  # files persist server-side; retry is safe

Prevention

When it happens

Trigger: Downloading files when the bearer token expired between get_file_list and the content GET, when the session is reclaimed mid-download, or on 5xx from the Azure Container Apps sessions endpoint. A network failure part-way through downloading multiple files aborts the remaining files.

Common situations: Long download sequences of many generated artifacts outliving the access token validity; transient service errors; racing with session idle-timeout during large outputs.

Related errors

AI-assisted analysis of microsoft/autogen@027ecf0a37 (2026-08-15). Data as JSON: /api/errors/5f34b6ac154da3ec. Report an issue: GitHub.