Running n8n cloud v2.9.4. When I add my Anthropic API key to the Anthropic Chat Model credential, I get:
“Couldn’t connect with these settings — The resource you are requesting could not be found”
What I’ve tried:
Key works perfectly via curl to /v1/messages endpoint
Created multiple new keys in the same workspace — same error
Deleted and recreated the credential in n8n multiple times
Left Base URL as default
A different API key from a separate Anthropic account works fine in n8n
Both keys use the same model (Sonnet 4.6)
Both keys return successful responses via curl
This seems like n8n’s credential validation is hitting an endpoint that my workspace doesn’t have access to, even though the actual messages API works fine. Is the credential test hitting something other than /v1/messages?
Hi @jonnyc
n8n’s backend validation is hardcoded to test your credential by pinging a specific model (usually Claude 3 Haiku). since your key is restricted to Sonnet, Anthropic blocks the test ping and throws a 404.
two ways to fix it:
1. just save it anyway. the actual workflow node will use Sonnet and execute perfectly. 2. temporarily enable Haiku in your Anthropic workspace, save the credential to get the green checkmark, then disable Haiku again.
I have the same problem. I am self-hosted on a synology nas drive running portainer.
Anthropic Credentials will save, but error immediately saying can’t connect. The node only lists depreciated models which also causes an error.
I have been dealing with this for 2 days and still have not solved it.
since you deleted and recreated the credential a few times, i think your node is still holding onto the internal ID of one of the old, deleted ones. when the workflow runs, it looks for that ghost ID and crashes.
just open the Anthropic Chat Model node and click the credential dropdown and re-select your newest credential and save the workflow.
also, skip looking for a Haiku toggle in Anthropic. you don’t need it. just link the new credential in the node, ignore n8n’s connection test error, and run your workflow.
@A_A4 Thanks for your help. Deleting the node, re adding it using Sonnet 4.5, and ignoring the error on save did work. I was then able to switch Sonnet 4.6.
There are an awful lot of bugs like this in the system. Pretty dissapointing.
totally get the frustration. n8n moves super fast and these hardcoded test pings definitely slip through . super annoying when it blocks a basic setup.
Good news: ignoring the error should work for most (assuming your API key is valid, of course). To be sure, I created a new Anthropic API credential today, saved and closed the dialog ignoring the “Couldn’t connect with these settings” message. Testing with the Anthropic Message a Model node showed it can query for a list of models and respond to a prompt.
Still frustrating, of course. No arguments.
The issue is in the credential check that happens on save. It’s missing a needed header, so Anthropic rejects it (appropriately so). There is an open issue on the n8n GitHub repo which was opened about a week ago (#26300). I submitted a fix tonight, but it may take some time to be approved, as there are over 900 pull requests waiting for review. I’m glad I don’t have a load like that, those open source maintainers deserve to be considered for sainthood.
