El Capitan & WD My Book

I am also having problems with El Capitan and WD My Book.  Not sure if i’m in the right thread…sorry if i’m not.  

Has someone found a solution?  I sent an email to customer support…hopefully I will hear from them soon.  

Welcome to the Community.

What issues are you encountering? Are you certain they relate to El Capitan and not a coincidental hard drive failure? Are you able to share the exact model of your hard drive since there are many WD Book family members? More information will allow for more Users to better help you.

I am having similar issues. My WD My Book will not mount now that I’ve upgraded to El Capitan. It appears for a couple of seconds in the Finder and I can even see the folders and files on the drive, then it immediately disconnects and an error appears about the drive not being disconnected properly. It remounts and disconnects in an endless loop until I unplug the drive. The same drive with the same USB cable mounts just fine on a different computer in my home running Yosemite. This drive worked great on the same day as my upgrade to El Capitan and has not mounted properly since. Any ideas? This is my Time Machine drive. It’s comforting to know that the drive is fine and mounts on my other computer, but I don’t want to have to buy a new drive since this one no longer connects to my primary Macbook Pro.

Exact same problem here.
See also Western digital showing in system report but not mounting El Captain