Merge pull request #293697 from PatAltimore/patricka-utf8-issue

Kafka control character issue

Author: prmerger-automator[bot]

articles/iot-operations/troubleshoot/known-issues.md

@@ -6,7 +6,7 @@ ms.author: dobett
 ms.topic: troubleshooting-known-issue
 ms.custom:
   - ignite-2023
-ms.date: 01/07/2025
+ms.date: 01/28/2025
 ---
 
 # Known issues: Azure IoT Operations
@@ -112,3 +112,5 @@ kubectl delete pod aio-opc-opc.tcp-1-f95d76c54-w9v9c -n azure-iot-operations
 - When connecting multiple IoT Operations instances to the same Event Grid MQTT namespace, connection failures may occur due to client ID conflicts. Client IDs are currently derived from dataflow resource names, and when using Infrastructure as Code (IaC) patterns for deployment, the generated client IDs may be identical. As a temporary workaround, add randomness to the dataflow names in your deployment templates.
 
 - When network connection is disrupted, Dataflows may encounter errors sending messages due to a mismatched producer ID. If you experience this issue, restart your Dataflows pods.
+
+- When using control characters in Kafka headers, you might encounter disconnections. Control characters in Kafka headers such as `0x01`, `0x02`, `0x03`, `0x04` are UTF-8 compliant but the IoT Operations MQTT broker rejects them. This issue happens during the data flow process when Kafka headers are converted to MQTT properties using a UTF-8 parser. Packets with control characters might be treated as invalid and rejected by the broker and lead to data flow failures.