I upgraded from Yosemite to El Capitan on 02/10/2015 on My IMac
and my IMac mini, and lost all my setting to bootcamp also to the external hard
drives that are attached to my IMacs and mini IMac, i.e. I cannot read or write to them. It's has taken
hours to reset the two computers.
Phil
Mac mini
And your question is?
A better place would be the El Capitan forum
https://discussions.apple.com/community/mac_os/os_x_el_capitan
FWIW, my 2011 Mini Server I am using as my home entertainment
center has no issues with the multiple external drives (USB and Firewire)
and network attached volumes.
What make/model external drives are you using and did you make the mistake
of installing their "helper apps" which neither really help and cause more problems
than they are worth and always create issues with OS upgrades.
El Capitan
