macOS reboot with latest Lightburn

I’m using the latest version of Lightburn (still just trialling but intend to register) and randomly when connected to my Emblaser 1 my Mac completely reboots without warning. All I can find in the system logs is:

My-MacBook-Pro-3967:DiagnosticReports <user_id_redacted>$ log show --predicate ‘eventMessage contains “Previous shutdown cause”’ --start “2020-04-06” --info --debug
Filtering the log data using “composedMessage CONTAINS “Previous shutdown cause””
Timestamp Thread Type Activity PID TTL
2020-04-07 10:35:40.540125+1000 0xb7 Default 0x0 0 0 kernel: (AppleSMC) Previous shutdown cause: -20

I’ve no idea what cause code -20 is; it doesn’t appear anywhere. I do see a lot of warnings about Lightburn massively exceeding wakeups - not sure if this is related or not…

Data Source: Microstackshots
Shared Cache: 0xcdbe000 44F3CDD4-8FAC-3139-A935-D0A7A3A3BD7F

Command: LightBurn
Path: /Applications/
Identifier: com.LightBurnSoftware.LightBurn
Version: ??? (???)
PID: 585

Event: wakeups
Action taken: none
Wakeups: 45001 wakeups over the last 159 seconds (282 wakeups per second average), exceeding limit of 150 wakeups per second over 300 seconds
Wakeups limit: 45000
Limit duration: 300s

This reboot happens whenever Lightburn is connected to my Emblaser - doesn’t matter with I’m running a job or if the Emblaser is sitting idle. Currently running macOS 10.14.5. I ran a 40 minute job earlier today and that was fine, but about 20 minutes after it finished I had a reboot. Seeing multiple a day and makes it difficult to trust if a job will be interrupted or not…


I’ve never heard of this, or ‘excessive wakeups’. The wakeups thing seems to be all over the net, but “-20” not so much. The only thing I could find with any sort of relevance was this:

And this:

Neither has great news - both users corrected the issue by reinstalling their OS’s. :confused:
Not much of a solution.

An Emblaser 1 is just a standard GRBL device, and we have a good number of those here.
Fewer using Macs, obviously, but this is the first I’ve heard of this one.

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