After upgraded to the latest firmware version (14.07.0), UM2 occasionally displayed the captioned error message. Not sure if it is related to the new firmware or it is a hardware issue.
Cold starting the machine again and usually it can work again. But sometimes it refused to print, and the print head's temperature is lower than normal (PLA not melted) even if the front panel displayed 210C or so. It seems the temperature reading is wrong.
Anyone has similar experience? Thanks.