error in middle of a print

Hello,
So, right in the middle.. or close to it around 40% complete... job failed and I finally dug through log files and found this... but it doesn't make any sense to me.
mcu 'mcu': Unable to open serial port: [Errno 2] could not open port /dev/btt-octopus-pro-446: [Errno 2] No such file or directory: '/dev/btt-octopus-pro-446'
U wasb;t even in the house when this happened so... i don't know what to make of this now. I had printed off 3 or 4 other prints earlier in the day, so it was working just fine