In https://lists.oasis-open.org/archives/mqtt-comment/201901/msg00001.html, Ken Borgendale, specification editor reports: Subject: End of public comments for MQTT v5.0 COS01 To: Date: Tue, 15 Jan 2019 16:53:52 -0600 The public comment period for MQTT Version 5.0 Candidate OASIS Standard 01 is now complete. The TC is aware of the following issues and plans to resolve these soon and move to a call for consent with either an unchanged specification or with minor non-material changes. Key Summary MQTT-535 CONNACK property length should be optional Minor Unresolved New MQTT-534 3.10.2.1.1 Property Length for UNSUBSCRIBE Packet references SUBSCRIBE Minor Unresolved Open MQTT-533 Missing UNSUBSCRIBE Packet in Packet List for Properties in Chapter 2.2.2 Minor Unresolved Open