标签：#customnode

What actually changed You built a custom n8n node with its own credential type. The node works in a workflow. You open the credential in the n8n UI, click Test , and instead of a green checkmark you get: No testing function found for this credential. You double-check the node — credentialTest is defined in methods , testedBy is set on the credential declaration, everything compiles. n8n just refuses to see it. This is one of the most-reported custom-node issues in n8n's history — the original report is Stack Overflow q/75109822 and the underlying bug is tracked in n8n-io/n8n#8188 , with users still reproducing it on 1.58+ and 1.94 well after the original fix landed. The fix The root cause is not a missing function. It is in LoadNodesAndCredentials.ts : n8n generates nodesToTestWith in dist/known/credentials.json but only reads supportedNodes when linking a credential to its test function. For custom and community nodes the two keys never match, so the linkage is dropped and the UI shows the "no testing function" message. The fix that survives across n8n versions is to stop relying on credentialTest on the node and instead define the test directly on the credential class as an ICredentialTestRequest . Before — the linkage that breaks // credentials/MyApi.credentials.ts import { ICredentialType , INodeProperties } from ' n8n-workflow ' ; export class MyApi implements ICredentialType { name = ' myApi ' ; displayName = ' My API ' ; // ❌ testedBy points at the node's credentialTest, which the loader // never resolves for custom/community nodes. testedBy = ' MyApiNode ' ; properties : INodeProperties [] = [ { displayName : ' API Key ' , name : ' apiKey ' , type : ' string ' , typeOptions : { password : true }, default : '' , }, ]; } // nodes/MyApi.node.ts export class MyApiNode implements INodeType { methods : INodeTypeMethods = { credentialTest : async ( credentials ) => { // n8n never calls this for a custom node. const res = await fetch ( ' https://api.example.com/me '