diff --git a/webclient/websocket/src/main/java/io/helidon/webclient/websocket/WsClientImpl.java b/webclient/websocket/src/main/java/io/helidon/webclient/websocket/WsClientImpl.java
index a2f74a49889..6c9717eed01 100644
--- a/webclient/websocket/src/main/java/io/helidon/webclient/websocket/WsClientImpl.java
+++ b/webclient/websocket/src/main/java/io/helidon/webclient/websocket/WsClientImpl.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023 Oracle and/or its affiliates.
+ * Copyright (c) 2023, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -74,6 +74,7 @@ class WsClientImpl implements WsClient {
 
         ClientRequestHeaders headers = http1Client.prototype().defaultRequestHeaders();
         headers.set(HEADER_UPGRADE_WS);
+        headers.set(HEADER_CONN_UPGRADE);
         headers.set(HEADER_WS_VERSION);
         headers.set(HeaderValues.CONTENT_LENGTH_ZERO);
         if (clientConfig.protocolConfig().subProtocols().isEmpty()) {
diff --git a/webserver/tests/websocket/src/main/java/io/helidon/webserver/tests/websocket/EchoService.java b/webserver/tests/websocket/src/main/java/io/helidon/webserver/tests/websocket/EchoService.java
index b2b9a4b44cf..6d554b0e3b2 100644
--- a/webserver/tests/websocket/src/main/java/io/helidon/webserver/tests/websocket/EchoService.java
+++ b/webserver/tests/websocket/src/main/java/io/helidon/webserver/tests/websocket/EchoService.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, 2023 Oracle and/or its affiliates.
+ * Copyright (c) 2022, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@
 import java.util.Optional;
 import java.util.concurrent.atomic.AtomicReference;
 
+import io.helidon.http.HeaderNames;
 import io.helidon.http.Headers;
 import io.helidon.http.HttpPrologue;
 import io.helidon.http.WritableHeaders;
@@ -54,6 +55,10 @@ public void onClose(WsSession session, int status, String reason) {
     @Override
     public Optional<Headers> onHttpUpgrade(HttpPrologue prologue, Headers headers) throws WsUpgradeException {
         WritableHeaders<?> upgradeHeaders = WritableHeaders.create();
+
+        if (!headers.get(HeaderNames.CONNECTION).get().equalsIgnoreCase("Upgrade")) {
+            throw new WsUpgradeException("Must include 'Connection' header with value 'Upgrade'");
+        }
         if (headers.contains(WsUpgrader.PROTOCOL)) {
             List<String> subProtocols = headers.get(WsUpgrader.PROTOCOL).allValues(true);
             if (subProtocols.contains("chat")) {