I upgraded my MacBookPro to El Capitan two days ago and this was a huge mistake: suddenly, all my external USB hard disks, including my TimeMachine backup (based on a huge Seagate disk), stopped completely working. Not only El Capitan does not show the disks in the Finder, but the Disk Utility does not see them any more. In the release notes of OS 10.11 beta, one could read:

  • USB Known Issues
    • USB storage devices, including internal SD card readers, may become unavailable after system sleep and require either re-plug or restart to recover.
    • USB input devices may become non-functional on some Macs after several days.
    • USB 1.0, 1.1 and older 2.0 devices may not function.

I have tried to reboot, reset the PRAM, reset the SMC, nothing works. Online fora are full of people experiencing blocking issues with USB since they upgraded to El Capitan. The issue was reported by many people during the beta program of OS 10.11 and nothing changed.

This is lame and not at the Apple « level ». Hurry up Apple, fix this.