diff --git a/extensions/vertx-http/deployment/src/main/java/io/quarkus/devui/deployment/menu/ContinuousTestingProcessor.java b/extensions/vertx-http/deployment/src/main/java/io/quarkus/devui/deployment/menu/ContinuousTestingProcessor.java
index 08787c427ab8f..ed41598d1cf3c 100644
--- a/extensions/vertx-http/deployment/src/main/java/io/quarkus/devui/deployment/menu/ContinuousTestingProcessor.java
+++ b/extensions/vertx-http/deployment/src/main/java/io/quarkus/devui/deployment/menu/ContinuousTestingProcessor.java
@@ -203,4 +203,4 @@ private void registerGetResultsMethod(LaunchModeBuildItem launchModeBuildItem) {
     private static final String NAMESPACE = "devui-continuous-testing";
     private static final String DASH = "-";
 
-}
\ No newline at end of file
+}
diff --git a/extensions/vertx-http/runtime/src/main/java/io/quarkus/devui/runtime/comms/JsonRpcRouter.java b/extensions/vertx-http/runtime/src/main/java/io/quarkus/devui/runtime/comms/JsonRpcRouter.java
index dd29949c732ba..310437b29257a 100644
--- a/extensions/vertx-http/runtime/src/main/java/io/quarkus/devui/runtime/comms/JsonRpcRouter.java
+++ b/extensions/vertx-http/runtime/src/main/java/io/quarkus/devui/runtime/comms/JsonRpcRouter.java
@@ -197,7 +197,7 @@ private void route(JsonRpcRequest jsonRpcRequest, ServerWebSocket s) {
                 }
                 uni.subscribe()
                         .with(item -> {
-                            if (JsonRpcMessage.class.isAssignableFrom(item.getClass())) {
+                            if (item != null && JsonRpcMessage.class.isAssignableFrom(item.getClass())) {
                                 JsonRpcMessage jsonRpcMessage = (JsonRpcMessage) item;
                                 codec.writeResponse(s, jsonRpcRequest.getId(), jsonRpcMessage.getResponse(),
                                         jsonRpcMessage.getMessageType());
diff --git a/extensions/vertx-http/runtime/src/main/java/io/quarkus/devui/runtime/continuoustesting/ContinuousTestingJsonRPCService.java b/extensions/vertx-http/runtime/src/main/java/io/quarkus/devui/runtime/continuoustesting/ContinuousTestingJsonRPCService.java
index 6ca7ffa2a3532..7fc979b102c23 100644
--- a/extensions/vertx-http/runtime/src/main/java/io/quarkus/devui/runtime/continuoustesting/ContinuousTestingJsonRPCService.java
+++ b/extensions/vertx-http/runtime/src/main/java/io/quarkus/devui/runtime/continuoustesting/ContinuousTestingJsonRPCService.java
@@ -60,7 +60,6 @@ public String lastKnownResults() {
         return this.lastKnownResults;
     }
 
-    @NonBlocking
     public boolean start() {
         return invokeAction("start");
     }