UPS preventing MacPro from booting

[msbc]

I'm having some boot issues with my 5.1MP. It's powered by a UPS and connected by USB cable. Sometimes when I boot - both cold and warm - I see the apple logo and grey progress bar only makes it half way before the Mac shuts down. Checking log I see:
UPS: Shutting down due to power loss!

Anybody else experienced this issue?

Thanks,
Mark

 

[h9826790]

May be better to remove the UPS if it cause problem.

 

[bogg]

There was a thread a few weeks back, was due to some ups associated kext not being compatible with El Capitan or something like that (iirc)

 

[DanielCoffey]

What model and capacity of UPS is it and how old is the battery?

 

[msbc]

There was a thread a few weeks back, was due to some ups associated kext not being compatible with El Capitan or something like that (iirc)

Hmmm, that might be worth looking into. This has only started happening in the last few months - I've had the UPS since December 2014 - CyberPower 1500 VA / 900 Watts. Maybe it aligned with updating to EL?

 

[ActionableMango]

You probably already know this, but I'll mention it anyway on the off-chance that you don't...what's happening is that OS X thinks it's getting the "hey the power is out, so shut down safely before the battery runs out" message from the UPS.

I don't know what's causing this--perhaps the bad KEXT as mentioned above. But in the meantime you can unplug the USB connection as a temporary fix so you can boot up reliably until the underlying problem is solved. You'll still have UPS battery backup, it just won't shut down automatically.