USB changes in El Capitan

I have a APC Smart-UPS C1500 connected to my 2009 Mac pro and have no problem.

- Try resetting the SMC and NVRAM/PRAM

Intel-based Macs: Resetting the System Management Controller (SMC)

About NVRAM and PRAM

Hello I have the same issue with my iMac 27 5K and my APC UPS (BR550GI).

I try with another UPS (APC UPS BK350EI) but nothing changed; if the usb cable is connected the boot progress bar stop it over 75%, if the usb cable is disconnected the boot is OK; when the mac is running I can connect the usb cable and I can see the energy management panel in preferences.

I try the UPS BR550GI and the UPS BK350EI with another mac book air and with another iMac 27 (non retina) and the boot is OK also with the usb cable connected.

I try resetting SMC and NVRAM and I reinstall El Capitan on my iMac 27 5K but the problem is still here.

FWIW, I have an APC Back-UPS ES 750 (many years old) connected to my 2013, 27" iMac

and it is working just fine with El Capitan. Do you also have other USB devices plugged in?

If so, try disconnecting all and just plug in the UPS and see what happens. If that works,

you may need to play "musical devices" by moving the USB connections around to perhaps

find a combo that works. One of the quirks with desktop Macs, is that the USB ports on the back

are actually split between to different USB controllers with some internal peripherals connected to each

(IR receiver, Bluetooth controller, etc.).

Hello,

thanks for the replay.

The APC UPS is the only USB device plugged in my iMac 27" 5K late 2014. I try all the 4usb ports but always, if the usb cable is connected, the boot progress bar stop it over 75%.

I also try the APC UPS to another iMac 27" late 2009, but the boot is OK.

With Yosemite the boot is OK with iMac 27" 5K too.

Can you boot to Recovery?

OS X: About OS X Recovery - Apple Support

No, I can't.

I can boot in recovery mode only if I unplug the usb cable; otherwise the boot progress bar stop it over 75%.

Try to boot into Internet Recovery by holding down Command+Option+R at startup.

That bypasses El Capitain.

- If still not successful that usually indicates a hardware problem and an appointment at the Genius Bar of an Apple store is in order.

Apple Retail Store - Genius Bar

- If that works try a fresh install of El Capitan. If still problem that would indicate a bug in EC.

I looked in the Developers Library and discovered:

OS X v10.11 Changes

This article describes changes to USB in OS X v10.11.

• The USB stack is completely redesigned to increase stability and performance compared to Mac OS 10.10. Applications and third-party drivers for vendor-specific USB devices built with 10.10 SDK require no modification.
• Applications that use IOUSBLib APIs should continue to work with no modification. IOKit drivers that use IOUSBDevice and IOUSBInterface APIs should continue to load and be functional with no regressions.
• If you are developing a new IOKit driver that uses IOKIT USB APIs, please refer to the OS X v10.11 SDK for new API and classes such as IOUSBHostDevice and IOUSBHostInterface. New applications developed using the OS X v10.11 SDK should continue to use the IOUSBLib APIs.
• Different classes of USB devices should not exhibit any regression in functionality compared to the OS X v10.10 release.

So, there is clearly something going on in the new drivers that causes issues. The recommendation that this is due to faulty hard disk drive or other internal computer hardware is inconsistent with the presentation.

Booting to Internet Recovery will show if it is due to El Capitian.

I tried to boot in Internet recovery and the boot is OK.

Yesterday I tried a fresh install of El Capitan but nothing changed if I plug in the USB cable I can't boot the MAC.

That would indicate a problem with EC and the 2014 mac Mini.

Nothing yo can do except wait for a fix/OSX update

Report the problem to Apple:

http://www.apple.com/feedback/macmini.html

http://www.apple.com/feedback/macosx.html

Make sure you include saying that no problem with Internet Recovery but problem with booting to Recovery partiton and fresh install of EC.

Hello,

I have a slightly different usb problem with the exact Mac Mini: Late 2014 Mini.

My issue is usb keyboard. It will work when connected directly to the Mini, but won't work through my Anker USB3 hub.

Am I out of luck until Cupertino makes a fix?

Thanks

OK , thank you very much , I will send a report to Apple as soon as possible . Thanks again. Luca

Hello,

no news with OS X 10.11.1; the issue is still here. :-(

From 10.11 to 10.11.2 (15C27e), my iMac 27'' (mid 2014 full optional!) freezes only a few times at startup if the USB cable of the Backup-UPS power supply is connected.

But each time that OS X start up or restarts, if the USB UPS cable is connected, this window always appears:

<<Warning! You are using power supply with UPS. Save documents and shutdown your computer.>>

My UPS is a APC Power-Saving Back-UPS ES 8 Outlet 700VA 230V model ES 700G (now it is renamed BE700G-IT)

I suspect that this problem is associated to another serious issue: if the USB cable of the Backup-UPS power supply is connected, Time Machine does not perform properly the hourly backups.

If I disconnect the Backup-UPS cable from the USB port and I start OS X, instead, the hourly TM backup properly works.

Obviously, i tried also with some clean installations of El Capitan, stable or beta version, but the problem persists.

My UPS ES 700G by APC and with Lion and Yosemite it always worked well.

I sent various feedback to Apple, from site and with Feedback Assistant.