Comment 7 for bug 1530548

A better workaround (than hitting ctrl+alt+(F1-F7) keys and then Escape)
is to remove the boot options 'splash $vt_handoff'

You can do it 'live' after pressing the left shift key during boot and then the 'e' key.

-o-

You can actually enter the passphase while the dark blue screen (in Lubuntu) is displayed (without any help text and without feedback stars or dots). But it is confusing and would make most users think that the boot has failed. I did not think of it until I had a nights sleep ;-)