"Expected dict, got " I was following tutorial and encountered an error

[wan9wu]

I was following tutorial : https://langchain-ai.github.io/langgraph/tutorials/introduction/#part-5-manually-updating-the-state

I have this problem in chapters 4 and 5

code:

events = graph.stream(None, config, stream_mode="values")

for event in events:

    if "messages" in event:

        event["messages"][-1].pretty_print()

error:

---------------------------------------------------------------------------
InvalidUpdateError                        Traceback (most recent call last)
Cell In[15], [line 2](vscode-notebook-cell:?execution_count=15&line=2)
      [1](vscode-notebook-cell:?execution_count=15&line=1) events = graph.stream(None, config, stream_mode="values")
----> [2](vscode-notebook-cell:?execution_count=15&line=2) for event in events:
      [3](vscode-notebook-cell:?execution_count=15&line=3)     if "messages" in event:
      [4](vscode-notebook-cell:?execution_count=15&line=4)         event["messages"][-1].pretty_print()

File d:\wangwu\software\miniconda3\envs\langchain\Lib\site-packages\langgraph\pregel\__init__.py:946, in Pregel.stream(self, input, config, stream_mode, output_keys, interrupt_before, interrupt_after, debug)
    [943](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/pregel/__init__.py:943)         del fut, task
    [945](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/pregel/__init__.py:945) # panic on failure or timeout
--> [946](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/pregel/__init__.py:946) _panic_or_proceed(done, inflight, loop.step)
    [947](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/pregel/__init__.py:947) # don't keep futures around in memory longer than needed
    [948](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/pregel/__init__.py:948) del done, inflight, futures

File d:\wangwu\software\miniconda3\envs\langchain\Lib\site-packages\langgraph\pregel\__init__.py:1347, in _panic_or_proceed(done, inflight, step, timeout_exc_cls)
   [1345](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/pregel/__init__.py:1345)             inflight.pop().cancel()
   [1346](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/pregel/__init__.py:1346)         # raise the exception
-> [1347](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/pregel/__init__.py:1347)         raise exc
   [1349](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/pregel/__init__.py:1349) if inflight:
   [1350](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/pregel/__init__.py:1350)     # if we got here means we timed out
   [1351](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/pregel/__init__.py:1351)     while inflight:
   [1352](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/pregel/__init__.py:1352)         # cancel all pending tasks

File d:\wangwu\software\miniconda3\envs\langchain\Lib\site-packages\langgraph\pregel\executor.py:60, in BackgroundExecutor.done(self, task)
...
    [502](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/graph/state.py:502)     return value if value is not None else SKIP_WRITE
    [503](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/graph/state.py:503) else:
--> [504](file:///D:/wangwu/software/miniconda3/envs/langchain/Lib/site-packages/langgraph/graph/state.py:504)     raise InvalidUpdateError(f"Expected dict, got {input}")

InvalidUpdateError: Expected dict, got

My env is :

Python: 3.11.9
langchain: 0.2.10
langgraph: 0.1.11

[vbarda]

@wan9wu just reran the tutorial notebook and i am not getting those errors, could you maybe make a small reproducible example that generates the above error for you?

[wan9wu]

thanks for your help.

My code is exactly the same as the code in the tutorial. only repleace,Just changed the llm provider

I upload my ipynb file.

4_Human-in-the-loop.zip

[vbarda]

@wan9wu do you mind just pasting the exact code snippet that causes the error (with llm & graph definitions + .stream() calls)? thanks!

[wan9wu]

Hi @vbarda, I have just found that it works, and I did not change anything. Thanks for your help again!

[wan9wu]

I found that langgraph was upgraded to 0.1.14 and langchain was upgraded to 0.2.11. This upgrade may be working.