MQTT error message during start up of Domoticz Topic is solved

[HoogendoornJH]

I have several Shelly switches that communicate with Domoticz via MQTT. When Domoticz is started, I always get the message "Error: MQTT: Failed enabling TLS mode (tls_set(ShellyMQTT), return code: 3)". What could be the cause and how can this problem be solved?

[gizmocuz]

Do you use a certificate? If yes, it has a problem with this certificate. (maybe the format is wrong)

[HoogendoornJH]

Yeah, I think you are right. I could not find the certificate file, but I emptied the field for "CA filename" in "MQTT Client Gateway with LAN interface" hardware. Everything still seems to work and the error does not appear anymore.