langchain-ai
TypeError: 'NoneType' object is not iterable when resume is used in thread.submit command
Checked other resources
- [x] This is a bug, not a usage question. For questions, please use the LangChain Forum (https://forum.langchain.com/).
- [x] I added a clear and detailed title that summarizes the issue.
- [x] I read what a minimal reproducible example is (https://stackoverflow.com/help/minimal-reproducible-example).
- [x] I included a self-contained, minimal example that demonstrates the issue INCLUDING all the relevant imports. The code run AS IS to reproduce the issue.
Example Code
thread.submit(undefined, { command: { resume: [{"type": "accept"}] } });
Error Message and Stack Trace (if applicable)
Traceback (most recent call last):
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph_api/worker.py", line 134, in wrap_user_errors
await consume(stream, run_id, resumable)
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph_api/stream.py", line 332, in consume
raise e
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph_api/stream.py", line 316, in consume
async for mode, payload in stream:
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph_api/stream.py", line 251, in astream_state
event = await wait_if_not_done(anext(stream, sentinel), done)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph_api/asyncio.py", line 91, in wait_if_not_done
raise e.exceptions[0] from None
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/pregel/__init__.py", line 2768, in astream
async for _ in runner.atick(
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/pregel/write.py", line 101, in _awrite
self.do_write(
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/pregel/write.py", line 128, in do_write
write(_assemble_writes(writes))
^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/pregel/write.py", line 183, in _assemble_writes
if ww := w.mapper(w.value):
^^^^^^^^^^^^^^^^^
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/graph/state.py", line 1248, in _control_branch
for go in command.goto
^^^^^^^^^^^^
TypeError: 'NoneType' object is not iterable
During task with name '__start__' and id '17de729a-e0e0-aa69-dba1-583551ea7936'
Description
The update and goto parameters for Command are optional. I'm passing a resume parameter in App.tsx, but why am I getting the following error when it crashes?
Command definition:
export interface Command {
/**
* An object to update the thread state with.
*/
update?: Record<string, unknown> | [string, unknown][] | null;
/**
* The value to return from an `interrupt` function call.
*/
resume?: unknown;
/**
* Determine the next node to navigate to. Can be one of the following:
* - Name(s) of the node names to navigate to next.
* - `Send` command(s) to execute node(s) with provided input.
*/
goto?: Send | Send[] | string | string[];
}
App.tsx:
{thread.interrupt && (
<div className="mt-4 p-4 bg-yellow-700 rounded-md text-neutral-100">
<h3 className="text-lg font-bold mb-2">Tool Call</h3>
<p className="mb-4">Tool Call Request:</p>
<ReactMarkdown remarkPlugins={[remarkGfm]} className="markdown-body">
{JSON.stringify(thread.interrupt.value, null, 2)}
</ReactMarkdown>
<Button
onClick={() => {
thread.submit(undefined, { command: { resume: [{"type": "accept"}] } });
}}
className="bg-blue-500 hover:bg-blue-600 text-white font-bold py-2 px-4 rounded"
>
Continue
</Button>
</div>
)}
human_in_the_loop.py:
from typing import Callable, TypedDict, Optional
from langchain_core.tools import BaseTool, tool as create_tool
from langchain_core.runnables import RunnableConfig
from langgraph.types import interrupt
class HumanInterruptConfig(TypedDict, total=False):
allow_accept: bool
allow_edit: bool
allow_respond: bool
class ActionRequest(TypedDict):
action: str
args: dict
class HumanInterrupt(TypedDict):
action_request: ActionRequest
config: HumanInterruptConfig
description: str
def add_human_in_the_loop(
tool: Callable | BaseTool,
*,
interrupt_config: Optional[HumanInterruptConfig] = None,
) -> BaseTool:
"""Wrap a tool to support human-in-the-loop review."""
if not isinstance(tool, BaseTool):
tool = create_tool(tool)
if interrupt_config is None:
interrupt_config = {
"allow_accept": True,
"allow_edit": True,
"allow_respond": True,
}
@create_tool(
tool.name,
description=tool.description,
args_schema=tool.args_schema
)
async def call_tool_with_interrupt(config: RunnableConfig, **tool_input):
request: HumanInterrupt = {
"action_request": {
"action": tool.name,
"args": tool_input
},
"config": interrupt_config,
"description": "Please review the tool call"
}
response = interrupt([request])[0]
if response["type"] == "accept":
tool_response = await tool.ainvoke(tool_input, config)
elif response["type"] == "edit":
tool_input = response["args"]["args"]
tool_response = await tool.ainvoke(tool_input, config)
elif response["type"] == "response":
user_feedback = response["args"]
tool_response = user_feedback
else:
raise ValueError(f"Unsupported interrupt response type: {response['type']}")
return tool_response
return call_tool_with_interrupt
System Info
System Information
OS: Darwin OS Version: Darwin Kernel Version 23.5.0: Wed May 1 20:19:05 PDT 2024; root:xnu-10063.121.3~5/RELEASE_ARM64_T8112 Python Version: 3.12.8 (main, Jan 14 2025, 23:36:58) [Clang 19.1.6 ]
Package Information
langchain_core: 0.3.68 langchain: 0.3.26 langchain_community: 0.3.27 langsmith: 0.3.45 langchain_anthropic: 0.3.17 langchain_dashscope: 0.1.8 langchain_deepseek: 0.1.3 langchain_google_genai: 2.1.8 langchain_openai: 0.3.28 langchain_tavily: 0.2.7 langchain_text_splitters: 0.3.8 langgraph_api: 0.2.94 langgraph_cli: 0.3.4 langgraph_license: Installed. No version info available. langgraph_runtime: Installed. No version info available. langgraph_runtime_inmem: 0.5.0 langgraph_sdk: 0.1.73
Optional packages not installed
langserve
Other Dependencies
aiohttp: 3.11.18 aiohttp<4.0.0,>=3.8.3: Installed. No version info available. anthropic<1,>=0.57.0: Installed. No version info available. async-timeout<5.0.0,>=4.0.0;: Installed. No version info available. blockbuster<2.0.0,>=1.5.24: Installed. No version info available. click>=8.1.7: Installed. No version info available. cloudpickle>=3.0.0: Installed. No version info available. cryptography<45.0,>=42.0.0: Installed. No version info available. dashscope: 1.23.8 dataclasses-json<0.7,>=0.5.7: Installed. No version info available. filetype: 1.2.0 google-ai-generativelanguage: 0.6.18 httpx: 0.28.1 httpx-sse<1.0.0,>=0.4.0: Installed. No version info available. httpx>=0.25.0: Installed. No version info available. httpx>=0.25.2: Installed. No version info available. jsonpatch<2.0,>=1.33: Installed. No version info available. jsonschema-rs<0.30,>=0.20.0: Installed. No version info available. langchain-anthropic;: Installed. No version info available. langchain-aws;: Installed. No version info available. langchain-azure-ai;: Installed. No version info available. langchain-cohere;: Installed. No version info available. langchain-community;: Installed. No version info available. langchain-core<1.0.0,>=0.3.47: Installed. No version info available. langchain-core<1.0.0,>=0.3.51: Installed. No version info available. langchain-core<1.0.0,>=0.3.66: Installed. No version info available. langchain-core<1.0.0,>=0.3.68: Installed. No version info available. langchain-core>=0.3.64: Installed. No version info available. langchain-deepseek;: Installed. No version info available. langchain-fireworks;: Installed. No version info available. langchain-google-genai;: Installed. No version info available. langchain-google-vertexai;: Installed. No version info available. langchain-groq;: Installed. No version info available. langchain-huggingface;: Installed. No version info available. langchain-mistralai;: Installed. No version info available. langchain-ollama;: Installed. No version info available. langchain-openai;: Installed. No version info available. langchain-openai<1.0.0,>=0.3.9: Installed. No version info available. langchain-perplexity;: Installed. No version info available. langchain-text-splitters<1.0.0,>=0.3.8: Installed. No version info available. langchain-together;: Installed. No version info available. langchain-xai;: Installed. No version info available. langchain<1.0.0,>=0.3.26: Installed. No version info available. langgraph-api<0.3.0,>=0.2.67;: Installed. No version info available. langgraph-checkpoint>=2.0.23: Installed. No version info available. langgraph-checkpoint>=2.0.25: Installed. No version info available. langgraph-runtime-inmem<0.4.0,>=0.3.0;: Installed. No version info available. langgraph-runtime-inmem<0.6,>=0.5.0: Installed. No version info available. langgraph-sdk>=0.1.0;: Installed. No version info available. langgraph-sdk>=0.1.71: Installed. No version info available. langgraph>=0.2: Installed. No version info available. langgraph>=0.3.27: Installed. No version info available. langsmith-pyo3: Installed. No version info available. langsmith>=0.1.125: Installed. No version info available. langsmith>=0.1.17: Installed. No version info available. langsmith>=0.3.45: Installed. No version info available. numpy>=1.26.2;: Installed. No version info available. numpy>=2.1.0;: Installed. No version info available. openai-agents: Installed. No version info available. openai<2.0.0,>=1.86.0: Installed. No version info available. opentelemetry-api: 1.32.1 opentelemetry-exporter-otlp-proto-http: Installed. No version info available. opentelemetry-sdk: 1.32.1 orjson: 3.10.12 orjson>=3.10.1: Installed. No version info available. orjson>=3.9.7: Installed. No version info available. packaging: 24.2 packaging<25,>=23.2: Installed. No version info available. pydantic: 2.11.7 pydantic-settings<3.0.0,>=2.4.0: Installed. No version info available. pydantic<3.0.0,>=2.7.4: Installed. No version info available. pydantic>=2.7.4: Installed. No version info available. pyjwt>=2.9.0: Installed. No version info available. pytest: Installed. No version info available. python-dotenv>=0.8.0;: Installed. No version info available. PyYAML>=5.3: Installed. No version info available. requests: 2.32.3 requests-toolbelt: 1.0.0 requests<3,>=2: Installed. No version info available. rich: 14.0.0 SQLAlchemy<3,>=1.4: Installed. No version info available. sse-starlette<2.2.0,>=2.1.0: Installed. No version info available. sse-starlette>=2: Installed. No version info available. starlette>=0.37: Installed. No version info available. starlette>=0.38.6: Installed. No version info available. structlog<26,>=24.1.0: Installed. No version info available. structlog>23: Installed. No version info available. tenacity!=8.4.0,<10,>=8.1.0: Installed. No version info available. tenacity!=8.4.0,<10.0.0,>=8.1.0: Installed. No version info available. tenacity>=8.0.0: Installed. No version info available. tiktoken: 0.7.0 tiktoken<1,>=0.7: Installed. No version info available. truststore>=0.1: Installed. No version info available. typing-extensions>=4.7: Installed. No version info available. uvicorn>=0.26.0: Installed. No version info available. watchfiles>=0.13: Installed. No version info available. zstandard: 0.23.0
After upgraded to langgraph 0.6.2:
Traceback (most recent call last):
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph_api/worker.py", line 135, in wrap_user_errors
await consume(stream, run_id, resumable)
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph_api/stream.py", line 349, in consume
raise e
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph_api/stream.py", line 333, in consume
async for mode, payload in stream:
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph_api/stream.py", line 263, in astream_state
event = await wait_if_not_done(anext(stream, sentinel), done)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph_api/asyncio.py", line 91, in wait_if_not_done
raise e.exceptions[0] from None
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/pregel/main.py", line 2934, in astream
async for _ in runner.atick(
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/pregel/_runner.py", line 401, in atick
_panic_or_proceed(
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/pregel/_runner.py", line 511, in _panic_or_proceed
raise exc
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/pregel/_retry.py", line 137, in arun_with_retry
return await task.proc.ainvoke(task.input, config)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/_internal/_runnable.py", line 463, in ainvoke
ret = await self.afunc(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/pregel/_write.py", line 102, in _awrite
self.do_write(
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/pregel/_write.py", line 129, in do_write
write(_assemble_writes(writes))
^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/pregel/_write.py", line 184, in _assemble_writes
if ww := w.mapper(w.value):
^^^^^^^^^^^^^^^^^
File "/Users/leopeng1995/workspaces/promptcn/deep-insight/.venv/lib/python3.12/site-packages/langgraph/graph/state.py", line 1252, in _control_branch
for go in goto_targets:
^^^^^^^^^^^^
TypeError: 'NoneType' object is not iterable
During task with name '__start__' and id '19dc15fb-f9f0-d6fd-bef9-1b174d17f8d8'
we are using 0.6.10 and got exact same issue, any hints ?
TypeError("'NoneType' object is not iterable")Traceback (most recent call last):
File "/usr/local/lib/python3.12/site-packages/langgraph/pregel/__init__.py", line 2830, in astream
async for _ in runner.atick(
File "/usr/local/lib/python3.12/site-packages/langgraph/pregel/write.py", line 114, in _awrite
self.do_write(
File "/usr/local/lib/python3.12/site-packages/langgraph/pregel/write.py", line 142, in do_write
write(_assemble_writes(writes))
^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/langgraph/pregel/write.py", line 199, in _assemble_writes
if ww := w.mapper(w.value):
^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/langgraph/graph/state.py", line 1079, in _control_branch
for go in command.goto
^^^^^^^^^^^^
TypeError: 'NoneType' object is not iterable
During task with name '__start__' and id '07550128-d02a-8832-204d-460fe083b6ec'
Root Cause:
The [Command] class had goto with a default value of () (empty tuple), but it could still be set to None The [_control_branch] function assumed goto would always be iterable, but didn't handle the None case
When command.goto was None, the code tried to iterate over None, causing the TypeError
Solution:
Updated [Command.goto] type annotation to explicitly allow None:
# Before
goto: Send | Sequence[Send | N] | N = ()
# After
goto: Send | Sequence[Send | N] | N | None = None
python
Fixed _control_branch function to handle None values:
# Before
goto_targets = (
[command.goto] if isinstance(command.goto, (Send, str)) else command.goto
)
# After
if command.goto is None:
goto_targets = ()
else:
goto_targets = (
[command.goto] if isinstance(command.goto, (Send, str)) else command.goto
)
@zhaohc10 Thanks for your reply! I'm not sure if this issue still exists after LangGraph was upgraded to 1.0.
what's the sepcific version you are using now? how about langgrap server version ? thx
I encountered this issue earlier while working on a personal project. I haven't been using the LangGraph JavaScript SDK recently, as I'm currently handling HITL resume through Python instead. This approach works fine for me, so I'm not sure whether this problem still exists in the newer version.
thank you for your reply, when ust HITL resume through Python, which langgrah version you are using, are you able to to only specifying resuem without goto filed
If you restart the HITL process through the Command in Python, it currently doesn't require passing the 'goto' parameter (just resume). I've tested this with both LangGraph 0.6.x and 1.0.x, which led me to believe the issue was with the LangGraph JavaScript SDK.
when invoke the resume command, were you using langgraph-sdk ? it works for me to without langgraph-sdk but it failed when using langgraph-sdk with command