diff --git a/proto/vtrpc.proto b/proto/vtrpc.proto
index 9d659ff4347..3352cfd83a2 100644
--- a/proto/vtrpc.proto
+++ b/proto/vtrpc.proto
@@ -169,6 +169,12 @@ enum Code {
 
   // DATA_LOSS indicates unrecoverable data loss or corruption.
   DATA_LOSS = 15;
+
+  // CLUSTER_EVENT indicates that a cluster operation might be in effect
+  CLUSTER_EVENT = 17;
+
+  // Topo server connection is read-only
+  READ_ONLY = 18;
 }
 
 // LegacyErrorCode is the enum values for Errors. This type is deprecated.