BackendTransportClosed is an error returned by backendpool.closedTripper indicating that the backend should not be used, but somehow it was still in usage.

NoBackend is the only error that can be returned by backendpool.Tripper (ErrUnknownBackend) It can happen on bug or wrong configuration (routing exists for not existing backend) or race in configuration.

NoConnToAllResolvedAddresses is an error returned by lbtransport.tripper when all addresses (IP:Port) returned by our resolver (K8s or DNS) are not accessible (dial errors).

NoResolutionAvailable is an error returned by lbtransport.tripper when we have an resolution error constantly and there is no (even old) resolution, so no target to even try.

NoRoute is an error returned by p.router.Route(req) indicating no route for given request.

RouteUnknownError is an error returned by p.router.Route(req) indicating some unknown error than no route.

TransportUnknownError.

Unauthorized is an error returned by proxy.AuthMiddleware indicating case when request is not authorized to be proxied.