DonHaul opened a new issue #9784: URL: https://github.com/apache/pulsar/issues/9784
**Describe the bug** A clear and concise description of what the bug is. When using a reader to read a single message from a partitioned topic the error The partitioned topic startMessageId is illegal appears: ``` Exception in thread "main" org.apache.pulsar.client.api.PulsarClientException: java.util.concurrent.ExecutionException: org.apache.pulsar.client.api.PulsarClientException: The partitioned topic startMessageId is illegal at org.apache.pulsar.client.api.PulsarClientException.unwrap(PulsarClientException.java:976) at org.apache.pulsar.client.impl.ReaderBuilderImpl.create(ReaderBuilderImpl.java:74) ``` I implemented the code in https://pulsar.apache.org/docs/en/client-libraries-java/#reader which works for non partitioned topics. I just consumed and saved the msg id bytes into a file and then loaded that file as the msg_id . Is any additional parameter needed to fetch partitioned topics? Consumer ``` Consumer consumer = client.newConsumer() .topic("apache/pulsar/test-topic") .subscriptionName("my-sub") .subscribe(); // Wait for a message Message msg = consumer.receive(); try { byte[] by = msg.getMessageId().toByteArray(); FileUtils.writeByteArrayToFile(new File(".\\msg.bytes"), by); }catch (Exception e){ System.out.println("ERROR"); e.printStackTrace(); } ``` Reader ``` byte[] msgIdBytes = FileUtils.readFileToByteArray(new File(".\\msg.bytes"));// Some message ID byte array System.out.println(msgIdBytes.length); MessageId id = MessageId.fromByteArray(msgIdBytes); System.out.println(id); Reader reader = client.newReader() .topic("apache/pulsar/test-topic") .startMessageId(id) .create(); Message message = reader.readNext(); // Process message System.out.println(message.getMessageId()); client.close(); ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org