Antrophic API key doesn't work in any way, been trying for 3 weeks now..

[FyrstNL]

Describe the problem/error/question

When configuring Anthropic credentials in N8N, the connection test fails even when a valid API key and correct Base URL (https://api.anthropic.com) are provided. The "Add Custom Header" toggle is enabled by default (or was toggled on), but no custom header values are required or filled in. This causes the credential test to fail.

What is the error message (if any)?

• "Please check the errors below"
• "Couldn't connect with these settings"
• "The resource you are requesting could not be found"

Please share your workflow/screenshots/recording

(workflow not included — sensitive credentials present)

The workflow consists of 4 nodes:

1. Webhook (GET)
2. Send a message (post: message)
3. Message a model / Anthropic node (message: text) — this is where the credential error occurs
4. Generate a prompt (generate: prompt)

Share the output returned by the last node

No output — the workflow cannot execute because the Anthropic credential test fails at setup.

Debug info

core

• n8nVersion: 2.10.4
• platform: docker (cloud)
• nodeJsVersion: 24.13.1
• nodeEnv: production
• database: sqlite
• executionMode: regular
• concurrency: 5
• license: enterprise (sandbox)

storage

• success: all
• error: all
• progress: false
• manual: true
• binaryMode: filesystem

pruning

• enabled: true
• maxAge: 168 hours
• maxCount: 2500 executions

client

• userAgent: mozilla/5.0 (macintosh; intel mac os x 10_15_7) applewebkit/537.36 (khtml, like gecko) chrome/146.0.0.0 safari/537.36
• isTouchDevice: false

Generated at: 2026-03-23T20:27:13.842Z

[n8n-assistant]

Hey @FyrstNL,

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-7431".

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-7431

[Joffcom]

Hey @FyrstNL

The credential test failing won't stop the workflow from running, can you try running the workflow and ignore the credential test error to see what happens.

[JordGasp]

Same here. The 'Test connection' fails in the UI, but the credential work just fine when the workflow actually runs.

[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.