External Drive Encryption and El Capitan not accepting unlock password

[apb87]

In case anyone else runs into this issue and wants to avoid a headache:

I backed up all of my files and a VM to an external drive and was in the process of encrypting it when I installed El Capitan. Once El Capitan installed, the external drive would not accept my unlock password. I wasn't sure if I forgot the password or not.

I was finally able to get into my drive by installing a Yosemite VM and transferring the files from the VM to my host El Capitan machine. (I don't have a second Mac, but it would likely be quicker to unlock the drive via a separate non-El Capitan mac.) I will leave it connected to the VM to allow the encryption process to complete and see if it will then appear under El Capitan..

TL;DR. External drive wouldn't mount/wouldn't accept unlock password. Current El Capitan beta has known issues with disk utility and usb devices, so I was able to circumvent the issue by connecting the drive to a Yosemite VM (or another Mac with Yosemite or earlier).

 

[Shirasaki]

I create a backup volume under el capitan and it is encrypted. Currently I have no issue.

I know this would not help, though.

 

[apb87]

Was yours already completely encrypted? I have a 3TB drive and it was only around 15% encrypted when I upgraded my machine to El Capitan, so that might be why yours had no issue since it wasn't still in the conversion process.

 

[Shirasaki]

Was yours already completely encrypted? I have a 3TB drive and it was only around 15% encrypted when I upgraded my machine to El Capitan, so that might be why yours had no issue since it wasn't still in the conversion process.

Mine is encrypted completely under el capitan, which should be the issue for you. You should wait until it completes encryption before installing el capitan.

By the way, I only encrypt a quarter of my whole volume.