Checked other resources

• This is a bug, not a usage question. For questions, please use the LangChain Forum (https://forum.langchain.com/).
• I added a clear and detailed title that summarizes the issue.
• I read what a minimal reproducible example is (https://stackoverflow.com/help/minimal-reproducible-example).
• 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

from langchain_core.messages import BaseMessage
from langchain_core.runnables import RunnableConfig
from langgraph.checkpoint.memory import MemorySaver
from langgraph.graph import StateGraph, START
from langgraph.types import Command
from langgraph.graph.message import add_messages
from typing import Annotated, TypedDict, Sequence

class State(TypedDict):
    messages: Annotated[Sequence[BaseMessage], add_messages]

def sub_sub_child(state):
    return Command(
        graph=Command.PARENT,
        goto="sub_child_3",
        update={"messages": state["messages"] + ["sub_sub_child executed, going to sub_child_3"]},
    )

sub_sub_builder = StateGraph(State)
sub_sub_builder.add_node("sub_sub_child", sub_sub_child)
sub_sub_builder.add_edge(START, "sub_sub_child")
sub_sub_graph = sub_sub_builder.compile(name="sub_sub_graph", checkpointer=True)

def sub_child_1(state):
    return {"messages": state["messages"] + ["sub_child_1 executed"]}

def sub_child_3(state):
    return {"messages": state["messages"] + ["sub_child_3 executed"]}

sub_builder = StateGraph(State)
sub_builder.add_node("sub_child_1", sub_child_1)
sub_builder.add_node("sub_child_2", sub_sub_graph)
sub_builder.add_node("sub_child_3", sub_child_3)
sub_builder.add_edge(START, "sub_child_1")
sub_builder.add_edge("sub_child_1", "sub_child_2")
sub_graph = sub_builder.compile(name="sub_graph", checkpointer=True)

def child_1(state):
    return {"messages": state["messages"] + ["child_1 executed"]}

builder = StateGraph(State)
builder.add_node("child_1", child_1)
builder.add_node("child_2", sub_graph)
builder.add_edge(START, "child_1")
builder.add_edge("child_1", "child_2")
graph = builder.compile(name="main_graph", checkpointer=MemorySaver())

result = graph.invoke({"messages":[]}, RunnableConfig(recursion_limit=100, configurable={"thread_id": 1}))

Error Message and Stack Trace (if applicable)

langgraph.errors.ParentCommand: Command(graph='child_2|sub_child_2', update={'messages': [HumanMessage(content='child_1 executed', additional_kwargs={}, response_metadata={}, id='0d913850-1062-4395-a94b-1edccb9fc3e8'), HumanMessage(content='sub_child_1 executed', additional_kwargs={}, response_metadata={}, id='bce46bfc-5040-40e7-a080-04c735edcabe'), 'sub_sub_child executed, going to sub_child_3']}, goto='sub_child_3')

Description

I am working on a graph which has a sub-graph as one of its nodes. This sub-graph also has a sub-graph in it. So essentially, we have a parent graph (called main_graph), which has one sub-graph as its node (called sub_graph). This sub_graph also has a sub-graph as its node (called sub_sub_graph). Returning a Command from the sub_sub_graph's one node that targets its parent (which should be sub_graph) results in an error.

System Info

System Information

OS: Linux
OS Version: #1 SMP PREEMPT_DYNAMIC Wed Jan 15 08:02:15 EST 2025
Python Version: 3.12.0 (main, Aug 26 2024, 03:18:57) [GCC 8.5.0 20210514 (Red Hat 8.5.0-4)]

Package Information

langchain_core: 0.3.76
langchain: 0.3.27
langsmith: 0.4.4
langchain_openai: 0.3.27
langchain_text_splitters: 0.3.11
langgraph_sdk: 0.2.0
langgraph_supervisor: 0.0.29

Optional packages not installed

langserve

Other Dependencies

async-timeout<5.0.0,>=4.0.0;: Installed. No version info available.
httpx: 0.28.1
httpx>=0.25.2: Installed. No version info available.
jsonpatch<2.0,>=1.33: 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,>=0.3.66: Installed. No version info available.
langchain-core<1.0.0,>=0.3.72: Installed. No version info available.
langchain-core<2.0.0,>=0.3.75: Installed. No version info available.
langchain-core>=0.3.40: 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-perplexity;: Installed. No version info available.
langchain-text-splitters<1.0.0,>=0.3.9: Installed. No version info available.
langchain-together;: Installed. No version info available.
langchain-xai;: Installed. No version info available.
langgraph<0.7.0,>=0.6.0: Installed. No version info available.
langsmith-pyo3: Installed. No version info available.
langsmith>=0.1.17: Installed. No version info available.
langsmith>=0.3.45: 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: Installed. No version info available.
opentelemetry-exporter-otlp-proto-http: Installed. No version info available.
opentelemetry-sdk: Installed. No version info available.
orjson: 3.10.18
orjson>=3.10.1: Installed. No version info available.
packaging: 24.2
packaging>=23.2: Installed. No version info available.
pydantic: 2.10.6
pydantic<3.0.0,>=2.7.4: Installed. No version info available.
pydantic>=2.7.4: Installed. No version info available.
pytest: Installed. No version info available.
PyYAML>=5.3: Installed. No version info available.
requests: 2.32.4
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.
tenacity!=8.4.0,<10.0.0,>=8.1.0: Installed. No version info available.
tiktoken<1,>=0.7: Installed. No version info available.
typing-extensions>=4.7: Installed. No version info available.
zstandard: 0.23.0