Dec 25

It’s Christmas time, which is when I get a chance to upgrade my home servers. This year one of them needed a double-upgrade: 14.10 to 15.04 to 15.10.

After backing-up (which is essentially a tar command, more on that in another post), I proceeded with the first upgrade.

Everything seemed to go smoothly but on boot, the system dropped into an emergency mode shell.

At least it showed a couple of errors:

  1. acpi pcc probe failed
  2. error getting authority error initializing authority

After a quick search, I found that the first is actually just a warning and can be ignored (source). If I had more time, I would consider fixing the root cause.

The second one was a little more tricky. The error doesn’t really indicate the real problem but a few people have found it to be caused by an invalid fstab entry.

In the recovery shell, run the following command to find which one (thanks):

[code lang=”bash”]journalctl -xb[/code]

For most people, it’s due to having a UUID specified that no longer exists (either due to reformatting a drive or removing the disk all together). In my case it was because I had several tmpfs mounts which are no longer allowed:

tmpfs           /tmp           tmpfs   defaults,noatime           0 0
tmpfs           /var/lock      tmpfs   defaults,noatime           0 0
tmpfs           /var/run       tmpfs   defaults,noatime           0 0
tmpfs           /var/tmp       tmpfs   defaults,noatime           0 0


The error can be alleviated either by adding nofail to the options or just removing / commenting out the mount.

The reason I used a tmpfs (RAM disk) for /tmp and others was when I originally set up this server (and some others) the boot disk was an 8GB CompactFlash card. Temp files would create undesirable wear on the device but I’ve since moved this system to an SSD so that’s not an issue anymore. Hence, I just deleted the entries.

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