X_OAUTH_PROVIDER_UNKNOWN

the URL named a provider this app has not enabled

the :provider segment is not a known provider, or is one but was left out of defineAuth({ providers }); also providerFor() reaching for an id nothing registered. One refusal for all of them: distinguishing them would describe the app's configuration to an anonymous caller

registerOAuthProvider({ id: '<id>' }) if it is not built in, then add that id to defineAuth({ providers: [...] }) — the registration comes first because a segment nothing registered cannot be added to providers at all, so "add it" alone was an instruction that could not be followed. The list the fix prints is what is known here, never the subset this app enabled, and meta carries only { provider }