Comment 49 for bug 1386005

Adding onto this bug because I also have the same problem while running Ubuntu 15.04 on a Lenovo T450s.

As with the other users attempting to boot puts you into the decrypt screen with a nice empty password box, but keyboard strokes do not appear to register, as if the decryption password had not been selected. The keyboard does recognize ctrl+alt+delete, which reboots into grub and hence into the same text-based decryption window that lets you enter your password.

This is a recent problem for me. I upgraded to 15.04 some time ago, but the problem only really appeared within the last week, possibly due to a dist-upgrade to linux-image-3.19.0-28 or linux-image-3.19.0-30. Unfortunately I'm not sure which upgrade I did when, and what else came in at the same time (I let my laptop sit a little too long without rebooting).