Since my last message here is the result of my last tests: Test 1 upload of the scketch without any modification from the site "MYSensor". In Domoticz's log: -discover the node: 2018-01-06 11:25:42.251 MySensors: Node: 5, Sketch Name: IR Rec/Playback 2018-01-06 11:25:42.252 MySensors: Node: 5, Sketch Version: 2.0 -at the touch of the "1" key of the remote control registered in 20: 018-01-06 11:25:49.388 (Mysensor) Light/Switch (IR Command) -appearance of a new device MYSensor -and in serial monitor of the Arduino IDE: Received : 1 RC5 801 (12 bits) Found code for preset #20 TSP:MSG:SEND 5-5-0-0 s=2,c=1,t=33,pt=1,l=1,sg=0,ft=0,st=ok:20 When I activate the device -in Domoticz's log: 2018-01-06 11:26:55.759 User: Admin initiated a switch command (157/IR Command/Off) 2018-01-06 11:26:55.760 Error: MySensors: Light command received for unknown node_id: 20 and "error sending command to the switch, please verify device/hardware" -No events in serial monitor of the Arduino IDE. Test 2 I made a new installation of Domoticz with the image "domoticz-raspberrypi-sdcard-4834.img". Domoticz faith configured, I added my MySensor gateway alone without any other hardware, after discovering the node and adding the device to the switches, an action on this device and there oh miracle, it works! Then I updated Domoticz to version 3.8153 and after that the device does not work anymore! and "error sending command to the switch, please verify device/hardware"