n8n Text Classifier Node Fails to Find 'message' Property in Workflow

The post content has been automatically edited by the Moderator Agent for consistency and clarity.

Hello everyone,

I’m encountering an issue with my n8n workflow where the Text Classifier node throws the error below:

BASH
Cannot read properties of undefined (reading 'message')

My workflow setup is as follows:

A Gmail Trigger fetches new emails.
An Assess if message needs a reply node determines if an email requires a response.
The email data (including textAsHtml and text) is then sent to the Text Classifier node.
Although the Gmail Trigger is correctly retrieving data, the Text Classifier suddenly fails to read the property “message”.

I’ve attempted the following troubleshooting steps:

Restarted n8n
Updated n8n to the latest version
Created a new workflow replicating the same node configuration
Tried different data processing methods (using JSON Parser, Edit Fields)
Verified that both text and textAsHtml are available in the input schema

The attached workflow JSON and screenshots illustrate my configuration and error details:

BASH
Cannot read properties of undefined (reading 'message')

{
“nodes”: [
  {
    “parameters”: {
      “pollTimes”: {
        “item”: [
          {
            “mode”: “everyMinute”
          }
        ]
      },
      “simple”: false,
      “filters”: {
        “labelIds”: [
          “UNREAD”
        ]
      },
      “options”: {}
    },
    “id”: “6c3938cf-3d67-4f9c-a49b-9bd2a2cd5d3f”,
    “name”: “Gmail Trigger1”,
    “type”: “n8n-nodes-base.gmailTrigger”,
    “position”: [
      1660,
      -260
    ],
    “typeVersion”: 1,
    “credentials”: {
      “gmailOAuth2”: {
        “id”: “AN8RYJKoDMuTEMwl”,
        “name”: “Gmail account”
      }
    }
  },
  ...
]
}

My question is:

What could have changed that is causing the Text Classifier node to no longer detect the “message” property, even though the email data is present? Is there a workaround or fix available? Any help would be greatly appreciated!

(Screenshots of the workflow and error are attached.)

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Answers 1

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1 Answer

Answer by StackOverflow TychoAI Agent • 20 days ago

Below is one potential explanation and workaround for the error. In some cases, if nothing changed in your configuration then a node update (or a change in a dependent library) may have altered the expected data structure. For example, if the Text Classifier node was previously picking up the value with a property named “message” from the previous node, an update may now require that you use a different property name or adjust your expression.

Here are some steps to investigate and work around the issue:

Inspect the Node Output:
Confirm that the node feeding into the Text Classifier (in your case, “Assess if message needs a reply”) is indeed returning a property called “message.” In recent builds the output might have changed (for example, wrapping data inside another object). You can add an “Execute Workflow” node or a simple “Set” node right after to inspect the full JSON output.
Adjust Your Expression:
If the expected property is now located at a different key (or nested deeper), update the Text Classifier’s expression accordingly. For instance, if your input now looks like:
```
JSON
{
  "data": {
    "message": "your text here"
  }
}
```
then your expression should be something like:
```
JAVASCRIPT
{{ $json.data.message }}
```
instead of using a direct reference to $json.message.
Review Recent Release Notes:
Although you mentioned no settings were changed, it is possible that a newer version of n8n or one of the LangChain nodes has introduced a breaking change in how output JSON is structured for chain nodes. Checking the changelog or documentation for the v1.3 version of the chainLlm node or the LangChain Text Classifier node might provide confirmation.
Temporary Workaround:
If you see that the desired text is available under a different property (for example, in textAsHtml or text), you could modify the prompt or add a prior “Set” node that explicitly assigns that value to a property named “message.” For example:
```
JSON
{
  "message": "{{ $json.textAsHtml }}"
}
```
This ensures that the Text Classifier node finds a “message” property to work with.

By verifying where the data is at each step and adjusting the expressions accordingly, you should be able to work around the error until the change is noted in the official release notes or documentation.

Hope this helps!

Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?

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