diff --git a/apps/emqx/src/emqx_types.erl b/apps/emqx/src/emqx_types.erl
index 3361798cf..322cc1c05 100644
--- a/apps/emqx/src/emqx_types.erl
+++ b/apps/emqx/src/emqx_types.erl
@@ -190,8 +190,9 @@
     anonymous => boolean(),
     cn => binary(),
     dn => binary(),
-    %% extra attributes
-    client_attrs => client_attrs(),
+    %% Extra client attributes, commented out for bpapi spec backward compatibility.
+    %% This field is never used in RPC calls.
+    %% client_attrs => client_attrs(),
     atom() => term()
 }.
 -type client_attrs() :: #{binary() => binary()}.
diff --git a/apps/emqx/test/emqx_config_SUITE.erl b/apps/emqx/test/emqx_config_SUITE.erl
index 77fd28f11..01a5cc001 100644
--- a/apps/emqx/test/emqx_config_SUITE.erl
+++ b/apps/emqx/test/emqx_config_SUITE.erl
@@ -453,7 +453,8 @@ zone_global_defaults() ->
                 strict_mode => false,
                 upgrade_qos => false,
                 use_username_as_clientid => false,
-                wildcard_subscription => true
+                wildcard_subscription => true,
+                client_attrs_init => disabled
             },
         overload_protection =>
             #{