Cura for Lulzbot 3.6.8 (on Win 10, Intel quad core) crashes the instant the Update Firmware button is hit, apparently only if the printer's USB connection is first established via the Connect button. On relaunch, the firmware has not been updated. I see an older report that Cura crashes *after* updating the firmware, but in this case, the update does not occur.
Tried restarting the printer, relaunching the software, rebooting the computer, and all combinations of these three conditions before each attempt, although not in every possible sequence. At any rate, I think the update should work as long as the software and printer are both running and connected, regardless of other circumstances.
What worked was hitting the Update Firmware button *without* first establishing the connection. When the update was complete, Cura did not crash, and indicated the printer was then connected.
If my observations are correct and reproducible, the crash must happen from trying to open an already open connection at the top of the Firmware Update class, which should be pretty easy to remedy.
Anyway, great job otherwise on this version! Stuff that wouldn't slice at all before is slicing almost instantly.