Anthropic Can't Connect through native node, "requires x-api-key header"

[JQuinnC]

Describe the problem/error/question

When using an AI Agent and connecting the native Anthropic node, attempting to open a list of models results in "x-api-key" header required and 400 error. The API Key is confirmed as working.

What is the error message (if any)?

400

Please share your workflow/screenshots/recording

https://link.nldrive.ai/ltuos

(Select the nodes on your canvas and use the keyboard shortcuts CMD+C/CTRL+C and CMD+V/CTRL+V to copy and paste the workflow.)
⚠️ WARNING ⚠️ If you have sensitive data in your workflow (like API keys), please remove it before sharing.

{
"nodes": [
{
"parameters": {
"model": {
"__rl": true,
"mode": "list",
"value": "claude-sonnet-4-20250514",
"cachedResultName": "Claude 4 Sonnet"
},
"options": {}
},
"type": "@n8n/n8n-nodes-langchain.lmChatAnthropic",
"typeVersion": 1.3,
"position": [
2864,
2992
],
"id": "524e420e-8ca4-4edc-809f-d39665f05d5b",
"name": "Anthropic Chat Model",
"credentials": {
"anthropicApi": {
"id": "Kv4ZfLJR1g1OvG1F",
"name": "Anthropic N8N API"
}
}
}
],
"connections": {
"Anthropic Chat Model": {
"ai_languageModel": [
[]
]
}
},
"pinData": {},
"meta": {
"templateCredsSetupCompleted": true,
"instanceId": "08adab7c8b63de84efe734bd94412c66db38f295025c1987dffd566a19d60abe"
}
}

Share the output returned by the last node

Environment Information

n8n Version: 1.113.3
Platform: GCP Kubernetes
Node.js Version: 22.19.0
Environment: production
Database: PostgreSQL
Execution Mode: queue (not "scaling single-main")
Concurrency: -1
License: Community (self hosted)

Storage Configuration:

• Success executions: all
• Error executions: false
• Progress: false
• Manual executions: true
• Binary mode: memory

Pruning Configuration:

• Enabled: true
• Max age: 48 hours
• Max count: 10,000 executions

Security:

• Secure cookie: false

Client:

• User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/140.0.0.0 Safari/537.36
• Touch device: false

Generated at: 2025-10-13T13:46:28.312Z}

[Joffcom]

Hey @JQuinnC,

Thank you for reaching out! We’ve received your issue and are looking into it. To help us track this internally, we’ve created a Linear ticket with the reference: "GHC-5003".

We’ll keep you updated as we make progress, but if you have any additional details or context to share, feel free to add them here - it’s always helpful!

Thanks for your patience and for bringing this to our attention.

---

For INTERNAL use only: GHC-5003

[n8n-assistant]

Hi @JQuinnC 👋

Thanks so much for your patience while we’ve been improving n8n. We know it’s taken some time to review this issue, and we’re currently updating our triage process to better keep up with our growth.

There have been a lot of improvements in recent releases, so we’d really appreciate it if you could check whether this issue still occurs in the latest release.

When you have a moment, please copy and paste the checklist below as a comment so our system can update the status automatically:

[ ] I have updated to the latest stable version of n8n [please specify version number] and I am still experiencing this issue
[ ] Please close this issue – I am no longer experiencing it
[ ] Please close this issue – [please specify a reason]

If we don’t hear from you in the next 14 days this issue will be automatically closed, feel free to reopen - don’t forget to add the checklist above so that our automated systems notify us of the issue.

Thanks again for helping us keep n8n healthy and up-to-date 💚

[n8n-assistant]

As we haven’t heard back from you, we’re going to close this issue to keep things organized. But don’t worry, if you have more information or need further assistance, you’re welcome to reopen the issue anytime or create a new one. We’re always happy to help!

Thanks for reaching out and have a great day! If this was closed by mistake and you have been waiting for us let me know and I can also re-open it.

[JQuinnC]

I have upgraded to version 2.2.4 and tried again.

I am still encountering the same error when trying to select the Anthropic node for an AI Agent.