# InvalidUpdateError: Node \_\_copy\_\_ does not exist - LangGraph State Update Failure

**URL:** <https://forum.langchain.com/t/invalidupdateerror-node-copy-does-not-exist-langgraph-state-update-failure/1540>\
**Category:** LangGraph\
**Tags:** cloud, langsmith-studio, python-help\
**Created:** [September 15, 2025, 9:01pm UTC](https://forum.langchain.com/t/invalidupdateerror-node-copy-does-not-exist-langgraph-state-update-failure/1540 "2025-09-15T21:01:26Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Petar](https://yyz1.discourse-cdn.com/flex007/user_avatar/forum.langchain.com/petar/32/60_2.png) [@Petar](https://forum.langchain.com/u/Petar)\
**Post date:** [September 15, 2025, 9:01pm UTC](https://forum.langchain.com/t/invalidupdateerror-node-copy-does-not-exist-langgraph-state-update-failure/1540/1 "2025-09-15T21:01:26Z")

</div>

## **Description:**

I’m encountering a persistent `InvalidUpdateError` when attempting to update thread state in LangGraph API v0.4.20. The error occurs during state updates and suggests that a node named ` __copy__ ` doesn’t exist in my graph definition.

This is happening with langgraph dev –allow-blocking and i put some multiple inputs in studio

**Error Details:**

```auto
langgraph.errors.InvalidUpdateError: Node __copy__ does not exist

```

**Stack Trace Context:**

- Error occurs in `graph.aupdate_state()` → `abulk_update_state()` → `aperform_superstep()`
- Triggered during `POST /threads/{thread_id}/state` API call
- Using LangGraph API v0.4.20 with in-memory runtime v0.12.0

**Environment:**

- LangGraph API: 0.4.20
- LangGraph Runtime: langgraph-runtime-inmem 0.12.0
- Python: 3.13
- Development mode with `--allow-blocking`

**Graph Configuration:**  
My graph is defined with standard nodes and doesn’t explicitly reference any ` __copy__ ` node. The error suggests LangGraph is internally trying to access a node that doesn’t exist in my graph definition.

**Questions:**

1. What is the ` __copy__ ` node and when does LangGraph create it internally?
2. Is this related to state copying mechanisms during updates?
3. Are there specific graph configurations that could trigger this error?
4. Is this a known issue with the recent v0.4.20 update?

The error is blocking state updates entirely and preventing normal workflow execution. Any insights into the root cause or potential workarounds would be greatly appreciated.

---

<div class="post-metadata">

**Author:** ![catherine-langchain](https://avatars.discourse-cdn.com/v4/letter/c/3be4f8/32.png) [@catherine-langchain](https://forum.langchain.com/u/catherine-langchain)\
**Post date:** [September 16, 2025, 1:11am UTC](https://forum.langchain.com/t/invalidupdateerror-node-copy-does-not-exist-langgraph-state-update-failure/1540/2 "2025-09-16T01:11:10Z")

</div>

> [@Petar](#):
>
> `Node`

hey @Petar - would it be possible to share a minimally reproducible example?

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<div class="post-metadata">

**Author:** ![Petar](https://yyz1.discourse-cdn.com/flex007/user_avatar/forum.langchain.com/petar/32/60_2.png) [@Petar](https://forum.langchain.com/u/Petar)\
**Post date:** [September 17, 2025, 11:10am UTC](https://forum.langchain.com/t/invalidupdateerror-node-copy-does-not-exist-langgraph-state-update-failure/1540/3 "2025-09-17T11:10:01Z")

</div>

Fixed!