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 β€” 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...