diff --git a/src/SignalR/clients/java/signalr/src/main/java/com/microsoft/signalr/HubConnection.java b/src/SignalR/clients/java/signalr/src/main/java/com/microsoft/signalr/HubConnection.java
index 67669576e74d..a4d1e58c7dab 100644
--- a/src/SignalR/clients/java/signalr/src/main/java/com/microsoft/signalr/HubConnection.java
+++ b/src/SignalR/clients/java/signalr/src/main/java/com/microsoft/signalr/HubConnection.java
@@ -537,11 +537,15 @@ private void stopConnection(String errorMessage) {
      * @param args   The arguments to be passed to the method.
      */
     public void send(String method, Object... args) {
-        if (hubConnectionState != HubConnectionState.CONNECTED) {
-            throw new RuntimeException("The 'send' method cannot be called if the connection is not active.");
+        hubConnectionStateLock.lock();
+        try {
+            if (hubConnectionState != HubConnectionState.CONNECTED) {
+                throw new RuntimeException("The 'send' method cannot be called if the connection is not active.");
+            }
+            sendInvocationMessage(method, args);
+        } finally {
+            hubConnectionStateLock.unlock();
         }
-
-        sendInvocationMessage(method, args);
     }
 
     private void sendInvocationMessage(String method, Object[] args) {
@@ -605,26 +609,31 @@ Object[] checkUploadStream(Object[] args, List<String> streamIds) {
      */
     @SuppressWarnings("unchecked")
     public Completable invoke(String method, Object... args) {
-        if (hubConnectionState != HubConnectionState.CONNECTED) {
-            throw new RuntimeException("The 'invoke' method cannot be called if the connection is not active.");
-        }
+        hubConnectionStateLock.lock();
+        try {
+            if (hubConnectionState != HubConnectionState.CONNECTED) {
+                throw new RuntimeException("The 'invoke' method cannot be called if the connection is not active.");
+            }
 
-        String id = connectionState.getNextInvocationId();
+            String id = connectionState.getNextInvocationId();
 
-        CompletableSubject subject = CompletableSubject.create();
-        InvocationRequest irq = new InvocationRequest(null, id);
-        connectionState.addInvocation(irq);
+            CompletableSubject subject = CompletableSubject.create();
+            InvocationRequest irq = new InvocationRequest(null, id);
+            connectionState.addInvocation(irq);
 
-        Subject<Object> pendingCall = irq.getPendingCall();
+            Subject<Object> pendingCall = irq.getPendingCall();
 
-        pendingCall.subscribe(result -> subject.onComplete(),
-                error -> subject.onError(error),
-                () -> subject.onComplete());
+            pendingCall.subscribe(result -> subject.onComplete(),
+                    error -> subject.onError(error),
+                    () -> subject.onComplete());
 
-        // Make sure the actual send is after setting up the callbacks otherwise there is a race
-        // where the map doesn't have the callbacks yet when the response is returned
-        sendInvocationMessage(method, args, id, false);
-        return subject;
+            // Make sure the actual send is after setting up the callbacks otherwise there is a race
+            // where the map doesn't have the callbacks yet when the response is returned
+            sendInvocationMessage(method, args, id, false);
+            return subject;
+        } finally {
+            hubConnectionStateLock.unlock();
+        }
     }
 
     /**
@@ -638,32 +647,37 @@ public Completable invoke(String method, Object... args) {
      */
     @SuppressWarnings("unchecked")
     public <T> Single<T> invoke(Class<T> returnType, String method, Object... args) {
-        if (hubConnectionState != HubConnectionState.CONNECTED) {
-            throw new RuntimeException("The 'invoke' method cannot be called if the connection is not active.");
-        }
+        hubConnectionStateLock.lock();
+        try {
+            if (hubConnectionState != HubConnectionState.CONNECTED) {
+                throw new RuntimeException("The 'invoke' method cannot be called if the connection is not active.");
+            }
 
-        String id = connectionState.getNextInvocationId();
+            String id = connectionState.getNextInvocationId();
+            InvocationRequest irq = new InvocationRequest(returnType, id);
+            connectionState.addInvocation(irq);
 
-        SingleSubject<T> subject = SingleSubject.create();
-        InvocationRequest irq = new InvocationRequest(returnType, id);
-        connectionState.addInvocation(irq);
+            SingleSubject<T> subject = SingleSubject.create();
 
-        // forward the invocation result or error to the user
-        // run continuations on a separate thread
-        Subject<Object> pendingCall = irq.getPendingCall();
-        pendingCall.subscribe(result -> {
-            // Primitive types can't be cast with the Class cast function
-            if (returnType.isPrimitive()) {
-                subject.onSuccess((T)result);
-            } else {
-                subject.onSuccess(returnType.cast(result));
-            }
-        }, error -> subject.onError(error));
+            // forward the invocation result or error to the user
+            // run continuations on a separate thread
+            Subject<Object> pendingCall = irq.getPendingCall();
+            pendingCall.subscribe(result -> {
+                // Primitive types can't be cast with the Class cast function
+                if (returnType.isPrimitive()) {
+                    subject.onSuccess((T)result);
+                } else {
+                    subject.onSuccess(returnType.cast(result));
+                }
+            }, error -> subject.onError(error));
 
-        // Make sure the actual send is after setting up the callbacks otherwise there is a race
-        // where the map doesn't have the callbacks yet when the response is returned
-        sendInvocationMessage(method, args, id, false);
-        return subject;
+            // Make sure the actual send is after setting up the callbacks otherwise there is a race
+            // where the map doesn't have the callbacks yet when the response is returned
+            sendInvocationMessage(method, args, id, false);
+            return subject;
+        } finally {
+            hubConnectionStateLock.unlock();
+        }
     }
 
     /**
@@ -677,33 +691,46 @@ public <T> Single<T> invoke(Class<T> returnType, String method, Object... args)
      */
     @SuppressWarnings("unchecked")
     public <T> Observable<T> stream(Class<T> returnType, String method, Object ... args) {
-        String invocationId = connectionState.getNextInvocationId();
-        AtomicInteger subscriptionCount = new AtomicInteger();
-        InvocationRequest irq = new InvocationRequest(returnType, invocationId);
-        connectionState.addInvocation(irq);
-        ReplaySubject<T> subject = ReplaySubject.create();
-
-        Subject<Object> pendingCall = irq.getPendingCall();
-        pendingCall.subscribe(result -> {
-            // Primitive types can't be cast with the Class cast function
-            if (returnType.isPrimitive()) {
-                subject.onNext((T)result);
-            } else {
-                subject.onNext(returnType.cast(result));
-            }
-        }, error -> subject.onError(error),
-                () -> subject.onComplete());
-
-        Observable<T> observable = subject.doOnSubscribe((subscriber) -> subscriptionCount.incrementAndGet());
-        sendInvocationMessage(method, args, invocationId, true);
-        return observable.doOnDispose(() -> {
-            if (subscriptionCount.decrementAndGet() == 0) {
-                CancelInvocationMessage cancelInvocationMessage = new CancelInvocationMessage(invocationId);
-                sendHubMessage(cancelInvocationMessage);
-                connectionState.tryRemoveInvocation(invocationId);
-                subject.onComplete();
+        String invocationId;
+        InvocationRequest irq;
+        hubConnectionStateLock.lock();
+        try {
+            if (hubConnectionState != HubConnectionState.CONNECTED) {
+                throw new RuntimeException("The 'stream' method cannot be called if the connection is not active.");
             }
-        });
+
+            invocationId = connectionState.getNextInvocationId();
+            irq = new InvocationRequest(returnType, invocationId);
+            connectionState.addInvocation(irq);
+
+            AtomicInteger subscriptionCount = new AtomicInteger();
+            ReplaySubject<T> subject = ReplaySubject.create();
+            Subject<Object> pendingCall = irq.getPendingCall();
+            pendingCall.subscribe(result -> {
+                        // Primitive types can't be cast with the Class cast function
+                        if (returnType.isPrimitive()) {
+                            subject.onNext((T)result);
+                        } else {
+                            subject.onNext(returnType.cast(result));
+                        }
+                    }, error -> subject.onError(error),
+                    () -> subject.onComplete());
+
+            Observable<T> observable = subject.doOnSubscribe((subscriber) -> subscriptionCount.incrementAndGet());
+            sendInvocationMessage(method, args, invocationId, true);
+            return observable.doOnDispose(() -> {
+                if (subscriptionCount.decrementAndGet() == 0) {
+                    CancelInvocationMessage cancelInvocationMessage = new CancelInvocationMessage(invocationId);
+                    sendHubMessage(cancelInvocationMessage);
+                    if (connectionState != null) {
+                        connectionState.tryRemoveInvocation(invocationId);
+                    }
+                    subject.onComplete();
+                }
+            });
+        } finally {
+            hubConnectionStateLock.unlock();
+        }
     }
 
     private void sendHubMessage(HubMessage message) {
diff --git a/src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/HubConnectionTest.java b/src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/HubConnectionTest.java
index b5104919ab44..0ff3be7fd0d9 100644
--- a/src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/HubConnectionTest.java
+++ b/src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/HubConnectionTest.java
@@ -1608,6 +1608,15 @@ public void cannotInvokeBeforeStart()  {
         assertEquals("The 'invoke' method cannot be called if the connection is not active.", exception.getMessage());
     }
 
+    @Test
+    public void cannotStreamBeforeStart()  {
+        HubConnection hubConnection = TestUtils.createHubConnection("http://example.com");
+        assertEquals(HubConnectionState.DISCONNECTED, hubConnection.getConnectionState());
+
+        Throwable exception = assertThrows(RuntimeException.class, () -> hubConnection.stream(String.class, "inc", "arg1"));
+        assertEquals("The 'stream' method cannot be called if the connection is not active.", exception.getMessage());
+    }
+
     @Test
     public void doesNotErrorWhenReceivingInvokeWithIncorrectArgumentLength()  {
         MockTransport mockTransport = new MockTransport();
@@ -2036,7 +2045,7 @@ public void authorizationHeaderFromNegotiateGetsSetToNewValue() {
 
         TestHttpClient client = new TestHttpClient()
                 .on("POST", "http://example.com/negotiate", (req) -> {
-                    if(redirectCount.get() == 0){
+                    if (redirectCount.get() == 0) {
                         redirectCount.incrementAndGet();
                         redirectToken.set(req.getHeaders().get("Authorization"));
                         return Single.just(new HttpResponse(200, "", "{\"url\":\"http://testexample.com/\",\"accessToken\":\"firstRedirectToken\"}"));
diff --git a/src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/WebSocketTransportUrlFormatTest.java b/src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/WebSocketTransportUrlFormatTest.java
index 2631084a3424..1dbe653dcc1a 100644
--- a/src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/WebSocketTransportUrlFormatTest.java
+++ b/src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/WebSocketTransportUrlFormatTest.java
@@ -8,7 +8,6 @@
 import java.util.HashMap;
 import java.util.stream.Stream;
 
-import io.reactivex.Single;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
diff --git a/src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/sample/Chat.java b/src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/sample/Chat.java
index bd617fe88e45..5201a0915887 100644
--- a/src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/sample/Chat.java
+++ b/src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/sample/Chat.java
@@ -37,6 +37,6 @@ public static void main(String[] args) {
             hubConnection.send("Send", message);
         }
 
-        hubConnection.stop();
+        hubConnection.stop().blockingAwait();
     }
 }