Has anyone faced any issues with the external hard drives or pen-drives not being detected on a MacBook that has been upgraded to macOS Sierra 10.12?

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    Someone probably faced some issues with external drives connected to the USB interface. But answering "Yes" or "No" won't help you much. So better open Console.app and search for USB/drive related issues in the various log files and post the errors! You may have to initiate the errors by attaching the drives and watch the log at the same time. – klanomath Oct 15 '16 at 18:47

I own a brand new MacBook Pro 2016 and many external devices are not working or not even recognized anymore. For instance my Presonus audiobox USB audio interface is not working anymore.

I contacted Presonus and they told me it has to do with lower power to the USB ports. Supposedly Apple is trying to extend battery life this way.


No. This isn't a known issue on Sierra. Im sure you and some others are however seeing problems after the upgrade, but I would expect it to be a coupincidence and not a cause that you upgraded.

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