Hello,
I’ve had this issue for some time now and need help to fix it.
< [18:01:14] Error:MINTEMP triggered, system stopped! Heater_ID: bed
< [18:01:14] Error:Printer halted. kill() called!
Does this mean that the head bed wire is disconnected? Is it a common issue?
This just happened to me last week. One of the wires for the bed heater was eaten through by the chain. I replaced them both. To me it seems like a problem with the design or installation of the harness in the chain that goes to the bed.
So I took apart the bed, all there was no damaged wires at all. Put it back together and it kept killing and stopping due to the same error.
I then simply reset the board, upgraded the firmware and the error disappeared.
Maybe it was a glitch?
But Thank You 
I’m also getting this error and as a result, I can’t finish any of my current parts. My print time is about 4 - 5 hours for this one part in particular, and I frequently get this error sometime after 50% complete.
I’ve already updated the firmware so I’m suspecting that this is a bug in the latest lulzbot firmware. If I can downgrade I’ll try that next.
I checked the wires and I don’t see anything unusual. The wires don’t come anywhere near the belt for me.
Someone in this thread mentions bringing the machine in from the garage to get it out of the cold so I decided to try this. I had to warm the bed with a heat gun because the temp sensor was reading 15°c, so the prints wouldn’t start. With the gun, the temp came up to 17°c, and when the print started it immediately jumped up to something like 55 - 60 °c.
I just switched to octoprint earlier this night, thinking that maybe the issue was related to a USB-on-Mac problem, and thanks to octoprint’s logging, I noticed this peculiarity:
the bed temp spiked low momentarily a couple times
The print failed again.
https://pastebin.com/77FUsd4v
Send: N2563 G0 F6562.5 X59.976 Y123.8*92
Recv: T:195.23 /195.00 B:60.28 /60.00 @:70 B@:0
Recv: Error:MINTEMP triggered, system stopped! Heater_ID: bed
Changing monitoring state from 'Printing' to 'Error: MINTEMP triggered, system stopped! Heater_ID: bed
'
Recv: Error:Printer halted. kill() called!
This is going to indicate you have a partial break in your thermistor wire leading back to the board. Those sharp drops are when the board lost connection to the thermistor. If it remains unable to read temperature long enough, it will shut down the printer for safety reasons. (It cannot control a heating element it cannot sense.)
Reach out to support@lulzbot.com and they should be able to walk you through getting that fixed up. We hope this helps!