Hibernation disappeared in Ubuntu 16.04 after a kernel upgrade

Question

I enabled hibernation in a few computers by adding /etc/polkit-1/localauthority/50-local.d/com.ubuntu.enable-hibernate.pkla with this content:

[Re-enable hibernate by default]
  Identity=unix-user:*
  Action=org.freedesktop.upower.hibernate
  ResultActive=yes

[Re-enable hibernate by default for login1]
  Identity=unix-user:*
  Action=org.freedesktop.login1.hibernate
  ResultActive=yes

[Re-enable hibernate for multiple users by default in logind]
  Identity=unix-user:*
  Action=org.freedesktop.login1.hibernate-multiple-sessions
  ResultActive=yes

It worked well till a recent update on my ASUS X200MA.

The menu item disappeared and also the com.ubuntu.enable-hibernate.pkla is not there any more. I added it again, but it did not change anything.

Also pm-hibernate command does not do anything and dmesg shows nothing.

How can I find out what has happened?

On other computers hibernation still works.

Answer 1

After some effort to get a solution I recalled that recently I activated Secure Boot in UEFI for testing purposes.

It was enabled before, but it was not active because I did not enroll the keys.

After that the "Hibernate" menu item disappeared.

I have no idea how Secure Boot is related to the hibernation option, but after I disabled Secure Boot, it works again.