Hi, I too ran into a similar problem after upgrading to 3.6.1 from 3.5.1.So far my work around to at least get MQTT functioning again was to edit the mqtt conf file in Notepad running as Administrator C:\Program Files\DELL\WMS\wmsmqtt\mqtt.conf 1. First comment out these lines:# sslport 8443 # server_cert_path certSsl# server_cert_auth UGFzc3dvcmQ5MTE= 2. Check if you are missing this line in the conf file and if so readd itlockbox_url [URL] 3. Restart the MQTT service or reboot the server and check your clients afterwards It seems that the upgrade breaks the service. I installed the newest version on a clean test server and had no problems (of course) and both the MQTT and Secure MQTT service are running. This isn't a permanent fix but will get your clients talking again. 
Hi, we encountered that MQTT is reported as 'closed' by the ThinClients. A restart of the mqtt service will lead to following log entries:12.05.2022 18:11:38 [6] E:Exception caughtUnable to connect to the remote server12.05.2022 18:11:38 [6] I:Lock box key received as null12.05.2022 18:11:39 [6] E:Certificate error: keytool error: java.io.IOException: Keystore was tampered with, or password was incorrect12.05.2022 18:11:39 [6] E:LockBoxKey and Cert Password Error. Retrying... 112.05.2022 18:11:44 [6] I:Got API Response as System.Net.HttpWebResponse12.05.2022 18:11:44 [6] I:Getting some response from lockbox url12.05.2022 18:11:44 [6] E:The path contains invalid characters. Program will not continue   The older log is showing the step from working to not working. There was no change on the system during this time. 26.04.2022 17:31:52 [6] I:MessageQueueSize:0 AssignedClients:0 MessagsProcessed:0 EventQueuesProcessed:026.04.2022 17:31:52 [6] I:MessageQueueSize:0 AssignedClients:0 MessagsProcessed:0 EventQueuesProcessed:026.04.2022 17:31:52 [6] I:ConnGotten:0 ConnReturned:0 ConnAvailable:279999 MsgAvailable:7 n:0, read_n10, write_n226.04.2022 17:31:52 [6] I:pingReq=31566, accCount:5682, MsgAdd:7962, ThState:8:8:8974:8974, to:212, kaD:62026.04.2022 17:31:52 [6] I:Sessions:147 SubscriptionByTopic:14126.04.2022 17:31:52 [6] E:Pulse End-66997423426.04.2022 17:31:52 [6] E:Error Object reference not set to an instance of an object.Stack trace: at MQTTServer.MainService.ServiceMainProc()at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)at System.Threading.ThreadHelper.ThreadStart()26.04.2022 17:32:21 [6] E:Exception caughtUnable to connect to the remote server26.04.2022 17:32:21 [6] I:Lock box key received as null26.04.2022 17:32:22 [6] E:Certificate error: keytool error: java.io.IOException: Keystore was tampered with, or password was incorrect26.04.2022 17:32:22 [6] E:LockBoxKey and Cert Password Error. Retrying... 126.04.2022 17:32:27 [6] I:Got API Response as System.Net.HttpWebResponse26.04.2022 17:32:27 [6] I:Getting some response from lockbox url26.04.2022 17:32:27 [6] E:The path contains invalid characters. Program will not continue   A roll-back of the server into an earlier version is not bringing back a working mqtt service. Any suggestions or hints? Thanks!
MQTT E:LockBoxKey and Cert Password Error