langgraph/troubleshooting/errors/INVALID_CONCURRENT_GRAPH_UPDATE/

[giscus[bot]]

langgraph/troubleshooting/errors/INVALID_CONCURRENT_GRAPH_UPDATE/

Build language agents as graphs

https://langchain-ai.github.io/langgraph/troubleshooting/errors/INVALID_CONCURRENT_GRAPH_UPDATE/

[AndreiSolodinTR]

The example above fails with

File "/site-packages/langgraph/pregel/algo.py", line 293, in apply_writes
if channels[chan].update(vals) and get_next_version is not None:
^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/site-packages/langgraph/channels/binop.py", line 88, in update
self.value = self.operator(self.value, value)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: can only concatenate list (not "str") to list

[djprawns]

How can I reinitialize the "some_key" to an empty list after my map reduce concludes?

[vbarda]

you would need to do something like this https://github.com/langchain-ai/retrieval-agent-template/blob/main/src/retrieval_graph/state.py#L54 and add a node after map reduce that returns that "delete" value

[itsphily]

I'm using parallel execution but I would like to fan in into a dictionary, how do I do that.

[2shin0]

I practiced using the Docs code, but when I entered the code below, an index error occurred. It seems the tool call failed. How can I resolve this?

example_answer = await gen_answer(
{"messages": [HumanMessage(content=question["messages"][0].content)]}
)
example_answer["messages"][-1].content

IndexError Traceback (most recent call last)
in <cell line: 1>()
----> 1 example_answer = await gen_answer(
2 {"messages": [HumanMessage(content=question["messages"][0].content)]}
3 )
4 example_answer["messages"][-1].content

in gen_answer(state, config, name, max_str_len)
26 dumped = json.dumps(all_query_results)[:max_str_len]
27 ai_message: AIMessage = queries["raw"]
---> 28 tool_call = queries["raw"].tool_calls[0]
29 tool_id = tool_call["id"]
30 tool_message = ToolMessage(tool_call_id=tool_id, content=dumped)

IndexError: list index out of range