Comment 2 for bug 526321

The apport information in your report shows a root device of /dev/mapper/sda6_crypt. Are you using cryptsetup to decrypt this at boot time? What version of cryptsetup do you have installed?

It also shows that you're booting without the 'splash' option - why is this?

If you're using cryptsetup, plymouth should be included in the initramfs and already started before ever switching to the root filesystem, so it shouldn't matter what's listed as the start condition for plymouth.

The post-start command you've added in the plymouth job is definitely wrong.