Comment 7 for bug 1481536

I'm also experiencing this. I noticed the following in my /var/log/boot.log:

/run/lvm/lvmetad.socket: connect failed: No such file or directory
WARNING: Failed to connect to lvmetad. Falling back to internal scanning.
Reading all physical volumes. This may take a while...
Found volume group "ubuntu-vg" using metadata type lvm2
/run/lvm/lvmetad.socket: connect failed: No such file or directory
WARNING: Failed to connect to lvmetad. Falling back to internal scanning.
2 logical volume(s) in group "ubuntu-vg" now active
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
device-mapper: remove ioctl on sda5_crypt failed: Device or resource busy
Device sda5_crypt is still in use.

and then it boots normally.