'NoneType' object is not subscriptable with FinalAnswerTool

TL;DR

Upgrade smolagents past the release containing #614; if it is not released yet, install from main: pip install -e PATHTOSMOLAGENTSROOTDIRECTORY. I also replaced ToolCallingAgent by CodeAgent, the error log is different but it still does not work most of the time.

Steps

1. smolagents FinalAnswerTool crashing with "'NoneType' object is not subscriptable" (also seen as 'Error in generating tool call with model'): it is a bug in how the agent handles a model response with no tool calls (message.toolcalls is None), not your prompt or tool setup. Fixed by PR #614. Upgrade smolagents past the release containing #614; if it is not released yet, install from main: pip install -e PATHTOSMOLAGENTSROOT_DIRECTORY.

When to use

You are seeing this: https://github.com/huggingface/smolagents/issues/404: Issue huggingface/smolagents#404 (closed, 9 comments): I am trying to reproduce the agentic RAG cookbook example. Use this skill when you run into "'NoneType' object is not subscriptable with FinalAnswerTool".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Sources

• https://github.com/huggingface/smolagents/issues/404:

Issue gh:huggingface/smolagents#404: the reporter asked: Issue huggingface/smolagents#404 (closed, 9 comments): I am trying to reproduce the agentic RAG cookbook example. But I noticed that the FinalAnswerTool was almost always throwing me an error. I tried with gpt4o (AzureOpenAI) and mistral-large-2407 (OpenAI-compatible API). I also replaced ToolCallingAgent by CodeAgent, the error log is different but it still does not work most of the time. Error: "Error in generating tool call with model: 'NoneType' object is not subscriptable" The verified answer was: smolagents FinalAnswerTool crashing with "'NoneType' object is not subscriptable" (also seen as 'Error in generating tool call with model'): it is a bug in how the agent handles a model response with no tool calls (message.toolcalls is None), not your prompt or tool setup. Fixed by PR #614. Upgrade smolagents past the release containing #614; if it is not released yet, install from main: pip install -e PATHTOSMOLAGENTSROOT_DIRECTORY. Evidence thread: https://github.com/huggingface/smolagents/issues/404