Jeff Porten, TidBITS:
If you’re using or considering buying one of the new MacBook Pro models with the Touch Bar (see “New MacBook Pros Add Context-sensitive Touch Bar,” 27 October 2016), be aware that some people are seeing their machines shut down repeatedly and unexpectedly. The problem might be with external hard drives connected via Thunderbolt 3’s USB-C ports, which is, of course, the only way to connect them.
I began researching this after I was unable to copy a large number of files from one external USB drive to another using my new MacBook Pro. The copy was going to take a long time regardless, but when I came back to check on its status, my laptop was powered off and I had to start it up again manually. Restarting the copy additional times resulted in similar shutdowns.
In my case, I was presented with an error message telling me about the shutdown, with the messages “CPU Machine Check Architecture Error Dump” and “CATERR detected! No MCA data found” in the highly technical error report that automatically gets sent to Apple.
Hopefully, this issue, as well as the graphics glitching issue reported yesterday, is a sign of early days with a new architecture, and will be resolved either with a software update (best possible solution) or a design fix (with some repair path for early adopters).