Running Ubuntu 18.04, I changed from a swap partition to a swap file.

swapon -s (summary) and free show the swapfile with the new size. /etc/fstab was changed, permission on the swapfile changed and the swap partition was deleted. When there are updates (apt-get update and upgrade), I get this error:

Setting up amd64-microcode (3.20180524.1~ubuntu0.18.04.2) ...
update-initramfs: deferring update (trigger activated)
amd64-microcode: microcode will be updated at next boot
Processing triggers for libc-bin (2.27-3ubuntu1) ...
Processing triggers for initramfs-tools (0.130ubuntu3.1) ...
update-initramfs: Generating /boot/initrd.img-4.15.0-29-generic
W: initramfs-tools configuration sets RESUME=UUID=c5a2c6f4-b67c-4d95-bc23-8333ed6c0f11
W: but no matching swap device is available.

The UUID listed there is for the old swap partition. I didn't think a swap file has a UUID, but I am not sure about that. Everything else seems to work fine. How should I proceed to troubleshoot and fix this?

  • What does this show? sudo swapon --show? And: ls -lh /swapfile – oldfred Jul 30 '18 at 21:49
  • outputs are: NAME TYPE SIZE USED PRIO /swapfile file 3G 0B -2 and -rw------- 1 root root 3.0G Jul 10 13:00 /swapfile – rkeating Jul 30 '18 at 21:54
  • Those look essentially the same as mine. What does fstab show? Post above to preserve formatting. cat /etc/fstab – oldfred Jul 30 '18 at 23:28
  • Tried to post it above, but text was huge. Just going to put the last lines (about swap) here: # swap was on /dev/sdb5 during installation #UUID=c5a2c6f4-b67c-4d95-bc23-8333ed6c0f11 none swap #sw 0 0 # swap now in /swapfile /swapfile none swap sw 0 0 – rkeating Jul 31 '18 at 1:38
  • It's not an error, W: stands for Warning. – mook765 Aug 13 '19 at 15:45

That line is in /etc/initramfs-tools/conf.d/resume so try deleting it.

The file in question, /etc/initramfs-tools/conf.d/resume, hasn't even existed in an Ubuntu LTS release since 14.04. Deleting the one line it contained on an 18.04 system will never cause a problem. This is a great example of why a reinstall is preferable to an upgrade, sometimes old things get left which can later cause problems.

As for those who think blkid will produce anything at all for a swapfile, you are wrong, and the answer which suggest using blkid is non-responsive to the stated problem. Reread the question, there is no longer a swap partition.

As a comment suggested, a UUID for the swapfile may be produced with swaplabel, but it is left as an exercise for the reader to see if using that swapfile UUID in a configuration file which is no longer part of the Ubuntu system will actually fix anything, or just result in another UUID lookup failure.

  • 5
    +1 Yes. Delete it or replace with RESUME=NONE or make it a comment (put a # in the beginning of the line). – sudodus Jul 30 '18 at 21:36
  • 1
    Deleted it, reboot, reran apt update and upgrade. initramfs updated with no errors. Thanks! – rkeating Jul 30 '18 at 22:04
  • 3
    RESUME=NONE does not work on Ubuntu LTS 18.04. Deleting the line or RESUME= does work. – Serge Stroobandt Apr 3 '19 at 16:54
  • 1
    this screws up new debian and ubuntu installs. the answer below fixes it properly... just do that. – Eric Jul 21 '20 at 23:34
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    This answer is terrible advice. Please don't just delete stuff from Linux that you don't understand. How this is the accepted answer is baffling. Instead, follow the instruction in the other answers on using blkid to determine the correct swap partition UUID and substitute that! – dovetalk Jul 23 '20 at 21:55

Step 1:

$ sudo blkid

It will list get UUID of each device or partition on your system. Copy the UUID of swap partition.

Step 2:

$ sudo vim /etc/initramfs-tools/conf.d/resume

Replace the available UUID with paste the UUID which you just copied and save it.

Step 3:

$ sudo update-initramfs -u
  • 1
    'sudo swaplabel /swapfile' will actually show the UUID of swap FILE. sudo blkid shows partitions, not /swapfile. At least it is so in my case. Do you have a /swapfile created? – Gryu May 22 '20 at 15:00
  • This is the correct answer – Sam Protsenko Jun 8 '20 at 22:26
  • 3
    this should be the accepted answer. I hate those lazy "Delete it" answers. – Aries VII Jul 17 '20 at 10:55
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    This answer is invalid for this case. The OP stated: "The UUID listed there is for the old swap partition. I didn't think a swap file has a UUID". He is right. If he does not use a swap partition anymore, but a swap file, then there is no more UUID to deal with. So, this answer is out of purpose for this case. But, it can be useful for those that use a swap partition... – Laurent Simon Nov 12 '20 at 6:32

Editing /etc/fstab with new UUID of swap worked fine boot time reduced to 10 seconds from 2 mins

  • Perfect, but how is this related to no matching swap device available? – Marc Vanhoomissen Mar 11 '20 at 13:41
  • This has nothing to do with the problem, which is the RESUME swap partition in /etc/initramfs-tools/conf.d/resume. Not /etc/fstab! – dovetalk Jul 23 '20 at 21:58

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