diff --git a/platform-sdk/swirlds-common/src/main/java/com/swirlds/common/merkle/synchronization/LearningSynchronizer.java b/platform-sdk/swirlds-common/src/main/java/com/swirlds/common/merkle/synchronization/LearningSynchronizer.java
index 266a87ff41da..8a80829dc2e4 100644
--- a/platform-sdk/swirlds-common/src/main/java/com/swirlds/common/merkle/synchronization/LearningSynchronizer.java
+++ b/platform-sdk/swirlds-common/src/main/java/com/swirlds/common/merkle/synchronization/LearningSynchronizer.java
@@ -220,8 +220,13 @@ private List<MerkleNode> receiveTreesInParallel(final List<MerkleNode> toReceive
                 new StandardWorkGroup(threadManager, WORK_GROUP_NAME, breakConnection, reconnectExceptionListener);
 
         final List<AtomicReference<MerkleNode>> reconstructedRoots = new ArrayList<>(toReceive.size());
+
         final AsyncInputStream in = new AsyncInputStream(inputStream, workGroup, reconnectConfig);
         final AsyncOutputStream out = buildOutputStream(workGroup, outputStream);
+        // Async output can be started right away. Its internal queues for every view are initialized
+        // in sendAsync(). Async input is different, views are explicitly registered in it using
+        // registerView() method. This is why it is started below, after all tasks are created
+        out.start();
 
         final AtomicInteger runningCount = new AtomicInteger(toReceive.size());
         for (final MerkleNode root : toReceive) {
@@ -253,8 +258,9 @@ private List<MerkleNode> receiveTreesInParallel(final List<MerkleNode> toReceive
             });
         }
 
+        // All views have registered themselves in async input. It can now accept messages from the
+        // underlying input stream and put them to the right view's queues. It's time to start it
         in.start();
-        out.start();
 
         InterruptedException interruptException = null;
         try {
diff --git a/platform-sdk/swirlds-common/src/main/java/com/swirlds/common/merkle/synchronization/TeachingSynchronizer.java b/platform-sdk/swirlds-common/src/main/java/com/swirlds/common/merkle/synchronization/TeachingSynchronizer.java
index 1690722789a6..63f22d8b2e42 100644
--- a/platform-sdk/swirlds-common/src/main/java/com/swirlds/common/merkle/synchronization/TeachingSynchronizer.java
+++ b/platform-sdk/swirlds-common/src/main/java/com/swirlds/common/merkle/synchronization/TeachingSynchronizer.java
@@ -180,6 +180,10 @@ private void sendTreesInParallel(final List<TeacherSubtree> toSend) throws Inter
 
         final AsyncInputStream in = new AsyncInputStream(inputStream, workGroup, reconnectConfig);
         final AsyncOutputStream out = buildOutputStream(workGroup, outputStream);
+        // Async output can be started right away. Its internal queues for every view are initialized
+        // in sendAsync(). Async input is different, views are explicitly registered in it using
+        // registerView() method. This is why it is started below, after all tasks are created
+        out.start();
 
         final AtomicInteger running = new AtomicInteger(toSend.size());
         for (final TeacherSubtree subtree : toSend) {
@@ -202,8 +206,9 @@ private void sendTreesInParallel(final List<TeacherSubtree> toSend) throws Inter
             });
         }
 
+        // All views have registered themselves in async input. It can now accept messages from the
+        // underlying input stream and put them to the right view's queues. It's time to start it
         in.start();
-        out.start();
 
         workGroup.waitForTermination();
 
diff --git a/platform-sdk/swirlds-common/src/main/java/com/swirlds/common/merkle/synchronization/streams/AsyncOutputStream.java b/platform-sdk/swirlds-common/src/main/java/com/swirlds/common/merkle/synchronization/streams/AsyncOutputStream.java
index 14b6beb031b1..1bf6e03f61bb 100644
--- a/platform-sdk/swirlds-common/src/main/java/com/swirlds/common/merkle/synchronization/streams/AsyncOutputStream.java
+++ b/platform-sdk/swirlds-common/src/main/java/com/swirlds/common/merkle/synchronization/streams/AsyncOutputStream.java
@@ -33,6 +33,7 @@
 import java.util.Queue;
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.TimeUnit;
 import org.apache.logging.log4j.LogManager;
@@ -120,12 +121,13 @@ public AsyncOutputStream(
         this.workGroup = Objects.requireNonNull(workGroup, "workGroup must not be null");
         this.queueSize = config.asyncStreamBufferSize();
         this.streamQueue = new LinkedBlockingQueue<>(queueSize * config.maxParallelSubtrees());
-        this.viewMessages = new HashMap<>();
         this.alive = true;
         this.timeSinceLastFlush = new StopWatch();
         this.timeSinceLastFlush.start();
         this.flushInterval = config.asyncOutputStreamFlush();
         this.timeout = config.asyncStreamTimeout();
+
+        this.viewMessages = new ConcurrentHashMap<>();
     }
 
     /**
diff --git a/platform-sdk/swirlds-virtualmap/src/main/java/com/swirlds/virtualmap/internal/reconnect/TeacherPullVirtualTreeReceiveTask.java b/platform-sdk/swirlds-virtualmap/src/main/java/com/swirlds/virtualmap/internal/reconnect/TeacherPullVirtualTreeReceiveTask.java
index 7e96d44122b3..c7726100e68d 100644
--- a/platform-sdk/swirlds-virtualmap/src/main/java/com/swirlds/virtualmap/internal/reconnect/TeacherPullVirtualTreeReceiveTask.java
+++ b/platform-sdk/swirlds-virtualmap/src/main/java/com/swirlds/virtualmap/internal/reconnect/TeacherPullVirtualTreeReceiveTask.java
@@ -120,7 +120,7 @@ private void rateLimit() throws InterruptedException {
     private void run() {
         boolean success = false;
         try {
-            in.anticipateMessage(); // anticipate root node response
+            in.anticipateMessage(); // anticipate root node request
             while (true) {
                 rateLimit();
                 final PullVirtualTreeRequest request = in.readAnticipatedMessage(viewId);