diff --git a/modules/transport-netty4/src/internalClusterTest/java/org/elasticsearch/http/netty4/Netty4IncrementalRequestHandlingIT.java b/modules/transport-netty4/src/internalClusterTest/java/org/elasticsearch/http/netty4/Netty4IncrementalRequestHandlingIT.java
index 1e84f65cdd842..3095139ca4685 100644
--- a/modules/transport-netty4/src/internalClusterTest/java/org/elasticsearch/http/netty4/Netty4IncrementalRequestHandlingIT.java
+++ b/modules/transport-netty4/src/internalClusterTest/java/org/elasticsearch/http/netty4/Netty4IncrementalRequestHandlingIT.java
@@ -174,7 +174,7 @@ public void testClientConnectionCloseMidStream() throws Exception {
 
             // await stream handler is ready and request full content
             var handler = ctx.awaitRestChannelAccepted(opaqueId);
-            assertBusy(() -> assertNotNull(handler.stream.buf()));
+            assertBusy(() -> assertNotEquals(0, handler.stream.bufSize()));
 
             assertFalse(handler.streamClosed);
 
@@ -187,7 +187,7 @@ public void testClientConnectionCloseMidStream() throws Exception {
 
             // wait for resources to be released
             assertBusy(() -> {
-                assertNull(handler.stream.buf());
+                assertEquals(0, handler.stream.bufSize());
                 assertTrue(handler.streamClosed);
             });
         }
@@ -204,15 +204,13 @@ public void testServerCloseConnectionMidStream() throws Exception {
 
             // await stream handler is ready and request full content
             var handler = ctx.awaitRestChannelAccepted(opaqueId);
-            assertBusy(() -> assertNotNull(handler.stream.buf()));
+            assertBusy(() -> assertNotEquals(0, handler.stream.bufSize()));
             assertFalse(handler.streamClosed);
 
             // terminate connection on server and wait resources are released
             handler.channel.request().getHttpChannel().close();
             assertBusy(() -> {
-                // Cannot be simplified to assertNull.
-                // assertNull requires object to not fail on toString() method, but closing buffer can
-                assertTrue(handler.stream.buf() == null);
+                assertEquals(0, handler.stream.bufSize());
                 assertTrue(handler.streamClosed);
             });
         }
@@ -228,14 +226,14 @@ public void testServerExceptionMidStream() throws Exception {
 
             // await stream handler is ready and request full content
             var handler = ctx.awaitRestChannelAccepted(opaqueId);
-            assertBusy(() -> assertNotNull(handler.stream.buf()));
+            assertBusy(() -> assertNotEquals(0, handler.stream.bufSize()));
             assertFalse(handler.streamClosed);
 
             handler.shouldThrowInsideHandleChunk = true;
             handler.stream.next();
 
             assertBusy(() -> {
-                assertNull(handler.stream.buf());
+                assertEquals(0, handler.stream.bufSize());
                 assertTrue(handler.streamClosed);
             });
         }
diff --git a/modules/transport-netty4/src/main/java/org/elasticsearch/http/netty4/Netty4HttpRequestBodyStream.java b/modules/transport-netty4/src/main/java/org/elasticsearch/http/netty4/Netty4HttpRequestBodyStream.java
index 238faa7a9237e..ac3e3aecf97b9 100644
--- a/modules/transport-netty4/src/main/java/org/elasticsearch/http/netty4/Netty4HttpRequestBodyStream.java
+++ b/modules/transport-netty4/src/main/java/org/elasticsearch/http/netty4/Netty4HttpRequestBodyStream.java
@@ -37,12 +37,15 @@ public class Netty4HttpRequestBodyStream implements HttpBody.Stream {
     private final List<ChunkHandler> tracingHandlers = new ArrayList<>(4);
     private final ThreadContext threadContext;
     private ByteBuf buf;
-    private boolean hasLast = false;
     private boolean requested = false;
     private boolean closing = false;
     private HttpBody.ChunkHandler handler;
     private ThreadContext.StoredContext requestContext;
 
+    // used in tests
+    private volatile int bufSize = 0;
+    private volatile boolean hasLast = false;
+
     public Netty4HttpRequestBodyStream(Channel channel, ThreadContext threadContext) {
         this.channel = channel;
         this.threadContext = threadContext;
@@ -112,11 +115,12 @@ private void addChunk(ByteBuf chunk) {
             comp.addComponent(true, chunk);
             buf = comp;
         }
+        bufSize = buf.readableBytes();
     }
 
     // visible for test
-    ByteBuf buf() {
-        return buf;
+    int bufSize() {
+        return bufSize;
     }
 
     // visible for test
@@ -130,6 +134,7 @@ private void send() {
         var bytesRef = Netty4Utils.toReleasableBytesReference(buf);
         requested = false;
         buf = null;
+        bufSize = 0;
         try (var ignored = threadContext.restoreExistingContext(requestContext)) {
             for (var tracer : tracingHandlers) {
                 tracer.onNext(bytesRef, hasLast);
@@ -164,6 +169,7 @@ private void doClose() {
         if (buf != null) {
             buf.release();
             buf = null;
+            bufSize = 0;
         }
         channel.config().setAutoRead(true);
     }
diff --git a/modules/transport-netty4/src/test/java/org/elasticsearch/http/netty4/Netty4HttpRequestBodyStreamTests.java b/modules/transport-netty4/src/test/java/org/elasticsearch/http/netty4/Netty4HttpRequestBodyStreamTests.java
index 5ff5a27e2d551..d456bbecfbd20 100644
--- a/modules/transport-netty4/src/test/java/org/elasticsearch/http/netty4/Netty4HttpRequestBodyStreamTests.java
+++ b/modules/transport-netty4/src/test/java/org/elasticsearch/http/netty4/Netty4HttpRequestBodyStreamTests.java
@@ -67,7 +67,7 @@ public void testEnqueueChunksBeforeRequest() {
         for (int i = 0; i < totalChunks; i++) {
             channel.writeInbound(randomContent(1024));
         }
-        assertEquals(totalChunks * 1024, stream.buf().readableBytes());
+        assertEquals(totalChunks * 1024, stream.bufSize());
     }
 
     // ensures all received chunks can be flushed downstream
@@ -119,7 +119,7 @@ public void testReadFromChannel() {
         channel.writeInbound(randomLastContent(chunkSize));
 
         for (int i = 0; i < totalChunks; i++) {
-            assertNull("should not enqueue chunks", stream.buf());
+            assertEquals("should not enqueue chunks", 0, stream.bufSize());
             stream.next();
             channel.runPendingTasks();
             assertEquals("each next() should produce single chunk", i + 1, gotChunks.size());
diff --git a/muted-tests.yml b/muted-tests.yml
index ed52d0b6ab1a7..fb61bb7a02f88 100644
--- a/muted-tests.yml
+++ b/muted-tests.yml
@@ -223,12 +223,6 @@ tests:
 - class: org.elasticsearch.repositories.s3.RepositoryS3RestIT
   method: testReloadCredentialsFromKeystore
   issue: https://github.com/elastic/elasticsearch/issues/116811
-- class: org.elasticsearch.http.netty4.Netty4IncrementalRequestHandlingIT
-  method: testClientConnectionCloseMidStream
-  issue: https://github.com/elastic/elasticsearch/issues/116815
-- class: org.elasticsearch.http.netty4.Netty4IncrementalRequestHandlingIT
-  method: testServerExceptionMidStream
-  issue: https://github.com/elastic/elasticsearch/issues/116838
 - class: org.elasticsearch.xpack.searchablesnapshots.hdfs.SecureHdfsSearchableSnapshotsIT
   issue: https://github.com/elastic/elasticsearch/issues/116851
 - class: org.elasticsearch.xpack.esql.analysis.VerifierTests