Printer disconnecting mid print

My printer disconnected from Cura and stopped printing mid print a few days ago. Since then any time I try to start a print it disconnects during the start gcode while it is doing its initial heating of the extruder before wiping. It’s not always the same temperature at which it stops either. Additionally, if I just set it to heat up manually it will heat to whichever temperature I specify but something during its start phase before printing is causing issues.

I have updated the firmware and tried a different cord and a different USB port and a different computer. It will take commands from Cura when I connect it, but once it stops during the start gcode it disconnects from Cura completely.

I’m out of ideas, help!

If you have the option to print from an SD card I would give that a try, if the print stops while running from a SD card as well it will eliminate this being a communication issue of some kind.
Also, could you let us know what version of Cura you are currently working with? As well as the printer type you have? This will make it easier to give accurate and helpful directions since there are changes in layout from software version to software version and from printer to printer.
Since you have been running these prints through a USB cable your Cura.log might have some information on what is causing this issue. Here are the pathways to your Cura log if you are working with the new Cura LE software (if you are working with Legacy Cura the pathway will be the same up until the cura-lulzbot folder, instead you would just be looking for a folder just labeled cura and the version number folder would be a different number):


/Users//Library/Application Support/cura-lulzbot/3.2/cura-lulzbot.log
If you can find and post your Cura log we can look through there for any error messages that might explain the issues you are having.

In my history, this usually indicates a bad thermistor either in the toolhead or the heat bed or a broken wire in the two. The firmware tries to heat up the elements and if the thermistor doesn’t respond as the firmware expects, it stops the print with a thermal runaway error service halted. It’s a safety feature so your printer doesn’t heat without being able to measure the temperature correctly.

What version mini do you have and how many hours of printing on it?

Anyway, it’s possible it’s something else, but in 7000 hours I’ve had this happen 3-4 times and every time it was bad thermistor or a broken heater wire.