diff --git a/client/src/main/proto/spine/client/subscription.proto b/client/src/main/proto/spine/client/subscription.proto
index 43f065785b..2a5209556b 100644
--- a/client/src/main/proto/spine/client/subscription.proto
+++ b/client/src/main/proto/spine/client/subscription.proto
@@ -190,7 +190,7 @@ message Subscription {
     SubscriptionId id = 1 [(required) = true];
 
     // Represents the original topic for this subscription.
-    Topic topic = 2 [(required) = true, (validate) = true, (if_invalid).msg_format = "Invalid topic"];
+    Topic topic = 2 [(required) = true, (validate) = true];
 }
 
 // Enumeration of possible technical error reasons occurred in topic validation.
diff --git a/server/src/test/java/io/spine/server/stand/StandTest.java b/server/src/test/java/io/spine/server/stand/StandTest.java
index 3b997fb644..aa9d1b07b5 100644
--- a/server/src/test/java/io/spine/server/stand/StandTest.java
+++ b/server/src/test/java/io/spine/server/stand/StandTest.java
@@ -534,7 +534,7 @@ void notCancelNonExistent() {
         var nonExistingSubscription = Subscription.newBuilder()
                 .setId(Subscriptions.generateId())
                 .setTopic(Topic.newBuilder().setId(topicId).buildPartial())
-                .build();
+                .buildPartial();
         assertThrows(InvalidSubscriptionException.class,
                      () -> stand.cancel(nonExistingSubscription, noOpObserver()));
     }