Release a chunk when the request body read fails

client/src/main/java/org/asynchttpclient/netty/request/body/BodyChunkedInput.java

@@ -59,7 +59,14 @@ public ByteBuf readChunk(ByteBufAllocator alloc) throws Exception {
         }
 
         ByteBuf buffer = alloc.buffer(chunkSize);
-        Body.BodyState state = body.transferTo(buffer);
+        Body.BodyState state;
+        try {
+            state = body.transferTo(buffer);
+        } catch (Throwable t) {
+            // ChunkedWriteHandler only releases chunks it is handed, so a failed read would leak this one.
+            buffer.release();
+            throw t;
+        }
         progress += buffer.writerIndex();
         switch (state) {
             case STOP:

client/src/test/java/org/asynchttpclient/netty/request/body/BodyChunkedInputTest.java

@@ -0,0 +1,71 @@
+/*
+ *    Copyright (c) 2026 AsyncHttpClient Project. All rights reserved.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+package org.asynchttpclient.netty.request.body;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufAllocator;
+import org.asynchttpclient.request.body.Body;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class BodyChunkedInputTest {
+
+    @Test
+    public void readChunkReleasesTheChunkWhenTheBodyFails() {
+        IOException failure = new IOException("Stream closed");
+        FailingBody body = new FailingBody(failure);
+        BodyChunkedInput input = new BodyChunkedInput(body);
+
+        IOException thrown = assertThrows(IOException.class, () -> input.readChunk(ByteBufAllocator.DEFAULT));
+
+        assertSame(failure, thrown);
+        assertNotNull(body.target);
+        assertEquals(0, body.target.refCnt());
+    }
+
+    private static final class FailingBody implements Body {
+
+        private final IOException failure;
+        private ByteBuf target;
+
+        FailingBody(IOException failure) {
+            this.failure = failure;
+        }
+
+        @Override
+        public long getContentLength() {
+            return -1;
+        }
+
+        @Override
+        public BodyState transferTo(ByteBuf target) throws IOException {
+            this.target = target;
+            // Part of a chunk is written before the source fails, as a multipart body does.
+            target.writeByte('x');
+            throw failure;
+        }
+
+        @Override
+        public void close() {
+        }
+    }
+}

client/src/test/java/org/asynchttpclient/request/body/multipart/MultipartUploadTest.java

@@ -416,6 +416,10 @@ public void service(HttpServletRequest request, HttpServletResponse response) th
                 } catch (FileUploadException e) {
                     //
                 }
+                // The parser stops at the closing boundary, before a chunked body's terminating chunk if that has
+                // not arrived yet. Jetty then aborts the connection for unconsumed input once the response is
+                // done, and on Windows the reset discards the response before the client has read it.
+                request.getInputStream().transferTo(OutputStream.nullOutputStream());
                 try (Writer w = response.getWriter()) {
                     w.write(Integer.toString(getFilesProcessed()));
                     resetFilesProcessed();