After successfully upgraded to 16.04, I am now getting this message whilst booting
lvmetad not active yet, using direct access
This is an inofensive message and you should not worry about it.
If you do 'man lvmetad' you'll find that it is a daemon that caches disk metadata. If this daemon is not available, lvm will read the metadata from the disk. This may be a problem with very complex systems with hundreds of volumes, but it is not for a desktop.
Every message that says it has been solved by touching grub or after installing some packages, has probably solved by upgrading the system and recreating the grub configuration.
This is a very very low priority bug and was there in Ubuntu and Debian for a while. Probably will dissapear in a upgrade without doing anything.
I've got that message for a while and without any adverse condition.
People complaining to be unable to login are being affected by another error and should continue checking the logs to find it.
Thanks to @Kyle in this thread, you can stop this blocking your interactive ttys from appearing with the following:
I managed to resolve this for my machines by adjusting the grub configuration like so:
GRUB_CMDLINE_LINUX_DEFAULT="nomodeset"Then add this line:
GRUB_TERMINAL_INPUT="console serial"Run sudo update-grub and reboot for the changes to take effect.