diff --git a/src/Transports/Pulsar/Wolverine.Pulsar.Tests/FixMessageIdTests.cs b/src/Transports/Pulsar/Wolverine.Pulsar.Tests/FixMessageIdTests.cs
new file mode 100644
index 000000000..a4afc4030
--- /dev/null
+++ b/src/Transports/Pulsar/Wolverine.Pulsar.Tests/FixMessageIdTests.cs
@@ -0,0 +1,73 @@
+using DotPulsar;
+using Shouldly;
+using Xunit;
+
+namespace Wolverine.Pulsar.Tests;
+
+// Regression for the DotPulsar batch-handler partitioned-topic bug
+// (https://github.com/apache/pulsar-dotpulsar/issues/287). Builds on @patrick-cloke-simplisafe's
+// original repro in PR #2883; the only structural difference here is that PulsarListener now
+// reconstructs the partition sub-topic URI from the source consumer's own Topic
+// (IConsumer.Topic) rather than from _endpoint.PulsarTopic(). That additionally covers the
+// retry-consumer ack path - the retry consumer is subscribed to {baseTopic}-RETRY (or a
+// user-configured retry topic), so reusing the listener's base endpoint URI would have
+// reconstructed wrong sub-topic names and produced the same KeyNotFoundException on partitioned
+// retry topics.
+public class FixMessageIdTests
+{
+    private const string TopicUri = "persistent://public/default/events";
+    private const string RetryTopicUri = "persistent://public/default/events-RETRY";
+
+    [Fact]
+    public void FixMessageId_BatchMessageMissingTopic_ReconstructsPartitionTopic()
+    {
+        var messageId = new MessageId(1UL, 2UL, partition: 3, batchIndex: 0);
+
+        var result = PulsarListener.FixMessageId(messageId, TopicUri);
+
+        result.Topic.ShouldBe($"{TopicUri}-partition-3");
+        result.LedgerId.ShouldBe(1UL);
+        result.EntryId.ShouldBe(2UL);
+        result.Partition.ShouldBe(3);
+        result.BatchIndex.ShouldBe(0);
+    }
+
+    [Fact]
+    public void FixMessageId_TopicAlreadySet_ReturnsOriginal()
+    {
+        var messageId = new MessageId(1UL, 2UL, partition: 3, batchIndex: 0, topic: $"{TopicUri}-partition-3");
+
+        var result = PulsarListener.FixMessageId(messageId, TopicUri);
+
+        result.ShouldBeSameAs(messageId);
+    }
+
+    [Fact]
+    public void FixMessageId_NonPartitionedMessage_ReturnsOriginal()
+    {
+        var messageId = new MessageId(1UL, 2UL, partition: -1, batchIndex: -1);
+
+        var result = PulsarListener.FixMessageId(messageId, TopicUri);
+
+        result.ShouldBeSameAs(messageId);
+    }
+
+    [Fact]
+    public void FixMessageId_BatchMessageOnPartitionedRetryTopic_UsesRetryTopicForReconstruction()
+    {
+        // When the source consumer is the retry consumer, the listener passes that consumer's
+        // Topic - which is the retry topic URI, not the base topic URI. The reconstruction must
+        // therefore key the partition sub-topic off the retry topic so the ack lands on the
+        // correct sub-consumer inside DotPulsar's IConsumer._subConsumers map. Passing the base
+        // topic URI here (as the prior reconstruction did) would produce
+        // "events-partition-3" — a key the retry consumer's sub-consumers map does not contain —
+        // and re-trigger the same KeyNotFoundException the original bug reported on the main
+        // ack path.
+        var messageId = new MessageId(1UL, 2UL, partition: 3, batchIndex: 0);
+
+        var result = PulsarListener.FixMessageId(messageId, RetryTopicUri);
+
+        result.Topic.ShouldBe($"{RetryTopicUri}-partition-3");
+        result.Partition.ShouldBe(3);
+    }
+}
diff --git a/src/Transports/Pulsar/Wolverine.Pulsar/PulsarListener.cs b/src/Transports/Pulsar/Wolverine.Pulsar/PulsarListener.cs
index b1894ea99..8ae76fc80 100644
--- a/src/Transports/Pulsar/Wolverine.Pulsar/PulsarListener.cs
+++ b/src/Transports/Pulsar/Wolverine.Pulsar/PulsarListener.cs
@@ -158,7 +158,7 @@ public ValueTask CompleteAsync(Envelope envelope)
             var consumer = e.IsFromRetryConsumer && _retryConsumer != null ? _retryConsumer : _consumer;
             if (consumer != null)
             {
-                return consumer.Acknowledge(e.MessageData, _cancellation);
+                return consumer.Acknowledge(FixMessageId(e.MessageData.MessageId, consumer.Topic), _cancellation);
             }
         }
 
@@ -172,7 +172,7 @@ public async ValueTask DeferAsync(Envelope envelope)
         if (_enableRequeue && _sender is not null && envelope is PulsarEnvelope e)
         {
             var consumer = e.IsFromRetryConsumer && _retryConsumer != null ? _retryConsumer : _consumer;
-            await consumer!.Acknowledge(e.MessageData, _cancellation);
+            await consumer!.Acknowledge(FixMessageId(e.MessageData.MessageId, consumer.Topic), _cancellation);
             await _sender.SendAsync(envelope);
         }
     }
@@ -297,7 +297,7 @@ private async Task moveToQueueAsync(Envelope envelope, Exception? exception, boo
             }
 
             // Acknowledge the original message
-            await sourceConsumer!.Acknowledge(e.MessageData, _cancellation);
+            await sourceConsumer!.Acknowledge(FixMessageId(e.MessageData.MessageId, sourceConsumer.Topic), _cancellation);
 
             // Send copy to retry/DLQ topic
             await targetProducer.Send(messageMetadata, e.MessageData.Data, _cancellation)
@@ -305,6 +305,29 @@ await targetProducer.Send(messageMetadata, e.MessageData.Data, _cancellation)
         }
     }
 
+    /// <summary>
+    /// Workaround for https://github.com/apache/pulsar-dotpulsar/issues/287. DotPulsar's
+    /// <c>BatchHandler.Add</c> constructs the inner <see cref="MessageId" /> for each message of a
+    /// batch via the four-arg ctor and never sets <see cref="MessageId.Topic" />, so
+    /// <c>Consumer.Acknowledge</c> hits <c>_subConsumers[messageId.Topic]</c> with the empty
+    /// string and throws <see cref="System.Collections.Generic.KeyNotFoundException" /> on
+    /// partitioned topics. Reconstruct the <see cref="MessageId" /> with the partition sub-topic
+    /// URI built from the <see cref="IConsumer.Topic" /> the source consumer was subscribed to.
+    /// Using <c>consumer.Topic</c> rather than <c>_endpoint.PulsarTopic()</c> means the same
+    /// helper works for the retry consumer (which subscribes to <c>{baseTopic}-RETRY</c>) without
+    /// any branching — DotPulsar reports the actual subscribed topic per consumer.
+    /// </summary>
+    internal static MessageId FixMessageId(MessageId messageId, string consumerTopic)
+    {
+        if (string.IsNullOrEmpty(messageId.Topic) && messageId.Partition >= 0)
+        {
+            return new MessageId(messageId.LedgerId, messageId.EntryId, messageId.Partition,
+                messageId.BatchIndex, $"{consumerTopic}-partition-{messageId.Partition}");
+        }
+
+        return messageId;
+    }
+
     private MessageMetadata BuildMessageMetadata(Envelope envelope, PulsarEnvelope e, Exception? exception,
         bool isDeadLettered)
     {