Encrypted Time Machine drives no randomly not unlocking

[jesseshipley]

I'm seeing an issue crop up randomly throughout my company where encrypted Time Machine drives will no longer mount. Some of these will mount on other computers but not the machine they are set as a backup destination for. Even after wiping keychain entries nothing happens. I tried changing the password on the drives too to no avail. Has anyone else experienced this problem? I'm going to start destroying the CS volumes and creating new encrypted backups but I would like to avoid that if at all possible.

[gskibum]

This sounds lots like something I used to frequently encounter on several different Macs. Now I see it only once in a while if at all. It seems to have worked itself out with maintenance releases of Mavericks or Mountain Lion.

What I would encounter is upon attaching an encrypted drive I would get the keychain prompt, even though the drive credentials were already keychained. And it would never accept the password when supplied. I found if I just kept clicking "Cancel" (4-5 times) the volume would eventually mount. But like I mentioned, the problem has mostly resolved itself with time. I'm assuming Apple fixed something along the way.

[jesseshipley · Accepted solution]

I ended up being able to resolve this through a PRAM reset. I guess the system is storing something there that can get corrupted.