ios upgrade on 3850 switch

[yaredo70]

Hi All,

I have to upgrade 3850 switches to the latest ios version with an external Hard drive that is formatted to FAT16 and partitioned to 1GB but the switch didn't recognize it. 

switch#dir usbflash0:

%error opening usbflash0:/ (No such file or directory)

Any idea?

Thanks,

[Leo Laohoo]

Use a USB thumb drive and not an HDD.