diff --git a/api/apierror.go b/api/apierror.go
index 885eb2ec1a..2aee379f02 100644
--- a/api/apierror.go
+++ b/api/apierror.go
@@ -15,6 +15,7 @@ var (
 	ErrInvalidArgument  = &Error{Kind: codes.InvalidArgument.String(), response: &Response{resp: &http.Response{StatusCode: http.StatusBadRequest}}}
 	ErrPermissionDenied = &Error{Kind: codes.PermissionDenied.String(), response: &Response{resp: &http.Response{StatusCode: http.StatusForbidden}}}
 	ErrUnauthorized     = &Error{Kind: codes.Unauthenticated.String(), response: &Response{resp: &http.Response{StatusCode: http.StatusUnauthorized}}}
+	ErrUnimplemented    = &Error{Kind: codes.Unimplemented.String(), response: &Response{resp: &http.Response{StatusCode: http.StatusNotImplemented}}}
 	ErrInvalidListToken = &Error{Kind: "invalid list token", response: &Response{resp: &http.Response{StatusCode: http.StatusBadRequest}}}
 )