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⚠ Unverified draft — do not ship

This page was drafted from public sources and has not been confirmed against the live n8n platform. It is noindex until verified. Draft confidence: high.

To verify: Confirm the exact button label ('+ Chat Model' vs the connector tooltip) in the operator's n8n version, and that the model providers shown match what their instance has installed.

n8n

A Chat Model sub-node must be connected and enabled

What this means

Your AI Agent has no 'brain' attached. An AI Agent node can't run on its own — it needs a language model (like an OpenAI or Anthropic chat model) plugged into it, and that model node has to be turned on.

Why you're seeing this

  • No Chat Model sub-node connected to the AI Agent

    Common

    The AI Agent was added (or its model was removed) without a chat-model sub-node wired into the 'Chat Model' connector underneath it. This is the primary cause.

  • A Chat Model is connected but disabled

    Sometimes

    The model sub-node exists but was deactivated (greyed out), so the agent still sees no usable model.

  • Broken/lost connection after copy-paste or import

    Sometimes

    Copying nodes between workflows or importing JSON can drop the sub-node link. Frequency is an estimate.

How to fix it

  1. 1

    On the AI Agent node, look at the connectors along the bottom and click the '+' under 'Chat Model'.

    Screenshot slot — drop /screenshots/n8n-chat-model-sub-node-must-be-connected-step-1.png
  2. 2

    Pick a chat model provider (e.g. OpenAI Chat Model, Anthropic Chat Model) and select it.

    Screenshot slot — drop /screenshots/n8n-chat-model-sub-node-must-be-connected-step-2.png
  3. 3

    Open that chat-model sub-node, add/select valid credentials for the provider, and choose a model (e.g. gpt-4o-mini).

    Screenshot slot — drop /screenshots/n8n-chat-model-sub-node-must-be-connected-step-3.png
  4. 4

    Make sure the chat-model sub-node is enabled (not greyed-out). If it's disabled, right-click it and Activate it.

    Screenshot slot — drop /screenshots/n8n-chat-model-sub-node-must-be-connected-step-4.png
  5. 5

    If the connection still won't register after an import or copy-paste, select all the nodes, copy them into a brand-new workflow, and reconnect the chat model there.

    Screenshot slot — drop /screenshots/n8n-chat-model-sub-node-must-be-connected-step-5.png
Why this happens (the technical detail)

n8n's AI Agent is a 'root node' in a cluster: it orchestrates but delegates the actual text generation to a connected Chat Model sub-node. Without a connected, enabled model, the agent has no inference engine to call, so n8n blocks execution before any API request is made. Connections can be silently lost during JSON import or cross-workflow copy.

Sources

Unverified draft — pending review.