@THEPRFCTEN Make sure you are connected to the unit you are updating. Maybe cable connection can help but I switched my wifi off and then on next to the unit. Otherwise I got Business Error 9...

Hello. I installed the 1.4.0 to my M9 Plus V2.8 with the upgrade tool to one of the slaves and it was fine. Other one and master gave a BusinessError 9 at the end and did not upgrade. But when I...