Bad request - please check your parameters (item 0)

[Monica_Stavi]

Hey guys,

this topic drives me crazy and I have tried several things.

I have a very simple setup:

I’m currently building a very simple n8n workflow where an incoming chat message should be forwarded via Gmail.

Workflow Setup

• Trigger: When chat message received

• Action: Send a message (Gmail node)

• Gmail node configuration:

  • To: (external test address)

  • Subject: “a message from N8N”

  • Message: ={{ $json.chatInput }} (should pull the input from the trigger)

The full workflow JSON is attached.

---

The Issue

Whenever I run the workflow, the execution fails at the Gmail node.

Error shown in the UI:

Bad request - please check your parameters (item 0)
Precondition check failed.

Error details from the logs (screenshot 2):

{
  "error": {
    "code": 400,
    "message": "Precondition check failed.",
    "errors": [
      {
        "message": "Precondition check failed.",
        "domain": "global",
        "reason": "failedPrecondition"
      }
    ],
    "status": "FAILED_PRECONDITION"
  }
}

---

Expected Behavior

• The incoming chatInput value should be passed into the Gmail node and sent as an email message.

Actual Behavior

• The Gmail node fails immediately with HTTP 400 Bad Request.

• The error suggests that either required parameters are missing or invalid (“Precondition check failed”).

---

My questions:

• Has anyone encountered this specific error with the Gmail node before?

• Is there a required field I’m missing (e.g. From address, encoding, or Email type)?

• Could the problem be with the expression ={{ $json.chatInput }} not being passed correctly?

Thanks a lot for your help! It drives me crazy!!!

[moosa]

I tried send email with chat trigger.

may be your google apps does not have correct api permission or your gmail is not added as test email.

Google OAuth Authentication in n8n - From Setup to Connection