LLM Compiler Example - Replan action failing due to incorrect format

Checked other resources

[X] I added a very descriptive title to this issue.
[X] I searched the LangGraph/LangChain documentation with the integrated search.
[X] I used the GitHub search to find a similar question and didn't find it.
[X] I am sure that this is a bug in LangGraph/LangChain rather than my code.
[X] I am sure this is better as an issue rather than a GitHub discussion, since this is a LangGraph bug and not a design question.

Example Code

for step in chain.stream({"messages":
    [
        HumanMessage(
            content="Find the current temperature in Tokyo, then, respond with a flashcard summarizing this information"
        )
    ]}
):
    print(step)

Error Message and Stack Trace (if applicable)

{
    "name": "InvalidUpdateError",
    "message": "Expected dict, got [AIMessage(content='Thought: The search results provided do not contain the current temperature in Tokyo directly, making it impossible to respond accurately with a flashcard summarizing this information.'), SystemMessage(content='Context from last attempt: The information retrieved does not include the current temperature in Tokyo, which is necessary to create the flashcard summary as requested. A direct search for the current temperature in Tokyo or a weather report source that includes this information is needed.')]",
    "stack": "---------------------------------------------------------------------------
InvalidUpdateError                        Traceback (most recent call last)
Cell In[24], line 1
----> 1 for step in chain.stream({\"messages\":
      2     [
      3         HumanMessage(
      4             content=\"Find the current temperature in Tokyo, then, respond with a flashcard summarizing this information\"
      5         )
      6     ]}
      7 ):
      8     print(step)

File ~/workspace/PyriStage/langgraph/.venv/lib/python3.12/site-packages/langgraph/pregel/__init__.py:1020, in Pregel.stream(self, input, config, stream_mode, output_keys, interrupt_before, interrupt_after, debug)
   1017         break
   1019 # panic on failure or timeout
-> 1020 _panic_or_proceed(all_futures, loop.step)
   1021 # don't keep futures around in memory longer than needed
   1022 del done, inflight, futures

File ~/workspace/PyriStage/langgraph/.venv/lib/python3.12/site-packages/langgraph/pregel/__init__.py:1450, in _panic_or_proceed(futs, step, timeout_exc_cls)
   1448             inflight.pop().cancel()
   1449         # raise the exception
-> 1450         raise exc
   1452 if inflight:
   1453     # if we got here means we timed out
   1454     while inflight:
   1455         # cancel all pending tasks

File ~/workspace/PyriStage/langgraph/.venv/lib/python3.12/site-packages/langgraph/pregel/executor.py:60, in BackgroundExecutor.done(self, task)
     58 def done(self, task: concurrent.futures.Future) -> None:
     59     try:
---> 60         task.result()
     61     except GraphInterrupt:
     62         # This exception is an interruption signal, not an error
     63         # so we don't want to re-raise it on exit
     64         self.tasks.pop(task)

File /usr/local/Cellar/python@3.12/3.12.4/Frameworks/Python.framework/Versions/3.12/lib/python3.12/concurrent/futures/_base.py:449, in Future.result(self, timeout)
    447     raise CancelledError()
    448 elif self._state == FINISHED:
--> 449     return self.__get_result()
    451 self._condition.wait(timeout)
    453 if self._state in [CANCELLED, CANCELLED_AND_NOTIFIED]:

File /usr/local/Cellar/python@3.12/3.12.4/Frameworks/Python.framework/Versions/3.12/lib/python3.12/concurrent/futures/_base.py:401, in Future.__get_result(self)
    399 if self._exception:
    400     try:
--> 401         raise self._exception
    402     finally:
    403         # Break a reference cycle with the exception in self._exception
    404         self = None

File /usr/local/Cellar/python@3.12/3.12.4/Frameworks/Python.framework/Versions/3.12/lib/python3.12/concurrent/futures/thread.py:58, in _WorkItem.run(self)
     55     return
     57 try:
---> 58     result = self.fn(*self.args, **self.kwargs)
     59 except BaseException as exc:
     60     self.future.set_exception(exc)

File ~/workspace/PyriStage/langgraph/.venv/lib/python3.12/site-packages/langgraph/pregel/retry.py:26, in run_with_retry(task, retry_policy)
     24 task.writes.clear()
     25 # run the task
---> 26 task.proc.invoke(task.input, task.config)
     27 # if successful, end
     28 break

File ~/workspace/PyriStage/langgraph/.venv/lib/python3.12/site-packages/langchain_core/runnables/base.py:2878, in RunnableSequence.invoke(self, input, config, **kwargs)
   2876             input = context.run(step.invoke, input, config, **kwargs)
   2877         else:
-> 2878             input = context.run(step.invoke, input, config)
   2879 # finish the root run
   2880 except BaseException as e:

File ~/workspace/PyriStage/langgraph/.venv/lib/python3.12/site-packages/langgraph/utils.py:93, in RunnableCallable.invoke(self, input, config, **kwargs)
     91 kwargs = {**self.kwargs, **kwargs}
     92 if self.trace:
---> 93     ret = self._call_with_config(
     94         self.func, input, merge_configs(self.config, config), **kwargs
     95     )
     96 else:
     97     config = merge_configs(self.config, config)

File ~/workspace/PyriStage/langgraph/.venv/lib/python3.12/site-packages/langchain_core/runnables/base.py:1785, in Runnable._call_with_config(self, func, input, config, run_type, **kwargs)
   1781     context = copy_context()
   1782     context.run(_set_config_context, child_config)
   1783     output = cast(
   1784         Output,
-> 1785         context.run(
   1786             call_func_with_variable_args,  # type: ignore[arg-type]
   1787             func,  # type: ignore[arg-type]
   1788             input,  # type: ignore[arg-type]
   1789             config,
   1790             run_manager,
   1791             **kwargs,
   1792         ),
   1793     )
   1794 except BaseException as e:
   1795     run_manager.on_chain_error(e)

File ~/workspace/PyriStage/langgraph/.venv/lib/python3.12/site-packages/langchain_core/runnables/config.py:397, in call_func_with_variable_args(func, input, config, run_manager, **kwargs)
    395 if run_manager is not None and accepts_run_manager(func):
    396     kwargs[\"run_manager\"] = run_manager
--> 397 return func(input, **kwargs)

File ~/workspace/PyriStage/langgraph/.venv/lib/python3.12/site-packages/langgraph/pregel/write.py:98, in ChannelWrite._write(self, input, config)
     93 # process entries into values
     94 values = [
     95     input if write.value is PASSTHROUGH else write.value for write in entries
     96 ]
     97 values = [
---> 98     val if write.mapper is None else write.mapper.invoke(val, config)
     99     for val, write in zip(values, entries)
    100 ]
    101 values = [
    102     (write.channel, val)
    103     for val, write in zip(values, entries)
    104     if not write.skip_none or val is not None
    105 ]
    106 # write packets and values

File ~/workspace/PyriStage/langgraph/.venv/lib/python3.12/site-packages/langgraph/utils.py:102, in RunnableCallable.invoke(self, input, config, **kwargs)
    100     if accepts_config(self.func):
    101         kwargs[\"config\"] = config
--> 102     ret = context.run(self.func, input, **kwargs)
    103 if isinstance(ret, Runnable) and self.recurse:
    104     return ret.invoke(input, config)

File ~/workspace/PyriStage/langgraph/.venv/lib/python3.12/site-packages/langgraph/graph/state.py:543, in CompiledStateGraph.attach_node.<locals>._get_state_key(input, config, key)
    541     return value if value is not None else SKIP_WRITE
    542 else:
--> 543     raise InvalidUpdateError(f\"Expected dict, got {input}\")

InvalidUpdateError: Expected dict, got [AIMessage(content='Thought: The search results provided do not contain the current temperature in Tokyo directly, making it impossible to respond accurately with a flashcard summarizing this information.'), SystemMessage(content='Context from last attempt: The information retrieved does not include the current temperature in Tokyo, which is necessary to create the flashcard summary as requested. A direct search for the current temperature in Tokyo or a weather report source that includes this information is needed.')]"
}

Description

https://github.com/langchain-ai/langgraph/issues/1513 and https://github.com/langchain-ai/langgraph/issues/1459 are related issues.

The LLM Compiler example has a small issue which is erroring out of any Replan functionality. The above code is an example I have added to the Jupyter notebook, since none of the current examples require a replan. The _parse_joiner_output function should return a dict, but in the case of a replan it excludes the required {"messages": ... } formatting.

I have fixed this issue locally, added a Replan example, and will link a PR shortly in the comments.

System Info

langchain==0.2.15 langchain-anthropic==0.1.23 langchain-community==0.2.13 langchain-core==0.2.35 langchain-openai==0.1.23 langchain-text-splitters==0.2.2

MacOS Python 3.12.4

langchain-ai / langgraph