Comment 18 for bug 1577926

Just for reference:

I had the same problem on my digital ocean droplet (after a distro upgrade).

Problem solved after upgrade the kernel in the digital ocean administration site. More details you can see here[1].

In my case the upgrade was from 3.x to 4.x serie.

[1] https://www.digitalocean.com/community/tutorials/how-to-update-a-digitalocean-server-s-kernel