How to set the RESUME variable to override these issues?

I have an Ubuntu 18.10 dual boot with Windows 10. I think that because of the error below my Ubuntu crashes/hangs a lot lately at the time of reboot/startup.

$ sudo apt-get --with-new-pkgs upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following NEW packages will be installed: linux-headers-4.18.0-15 linux-headers-4.18.0-15-generic linux-image-4.18.0-15-generic linux-modules-4.18.0-15-generic linux-modules-extra-4.18.0-15-generic
The following packages will be upgraded: linux-generic linux-headers-generic linux-image-generic
3 upgraded, 5 newly installed, 0 to remove and 0 not upgraded.
Need to get 66.0 MB of archives.
After this operation, 329 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 cosmic-updates/main amd64 linux-modules-4.18.0-15-generic amd64 4.18.0-15.16 [13.4 MB]
Get:2 cosmic-updates/main amd64 linux-image-4.18.0-15-generic amd64 4.18.0-15.16 [8,154 kB]
Get:3 cosmic-updates/main amd64 linux-modules-extra-4.18.0-15-generic amd64 4.18.0-15.16 [32.7 MB]
Get:4 cosmic-updates/main amd64 linux-generic amd64 4.18.0.15.16 [1,868 B]
Get:5 cosmic-updates/main amd64 linux-image-generic amd64 4.18.0.15.16 [2,480 B]
Get:6 cosmic-updates/main amd64 linux-headers-4.18.0-15 all 4.18.0-15.16 [10.5 MB]
Get:7 cosmic-updates/main amd64 linux-headers-4.18.0-15-generic amd64 4.18.0-15.16 [1,195 kB]
Get:8 cosmic-updates/main amd64 linux-headers-generic amd64 4.18.0.15.16 [2,440 B]
Fetched 66.0 MB in 2min 25s (456 kB/s)
Selecting previously unselected package linux-modules-4.18.0-15-generic.
(Reading database ... 197143 files and directories currently installed.)
Preparing to unpack .../0-linux-modules-4.18.0-15-generic_4.18.0-15.16_amd64.deb ...
Unpacking linux-modules-4.18.0-15-generic (4.18.0-15.16) ...
Selecting previously unselected package linux-image-4.18.0-15-generic.
Preparing to unpack .../1-linux-image-4.18.0-15-generic_4.18.0-15.16_amd64.deb ...
Unpacking linux-image-4.18.0-15-generic (4.18.0-15.16) ...
Selecting previously unselected package linux-modules-extra-4.18.0-15-generic.
Preparing to unpack .../2-linux-modules-extra-4.18.0-15-generic_4.18.0-15.16_amd64.deb ...
Unpacking linux-modules-extra-4.18.0-15-generic (4.18.0-15.16) ...
Preparing to unpack .../3-linux-generic_4.18.0.15.16_amd64.deb ...
Unpacking linux-generic (4.18.0.15.16) over (4.18.0.14.15) ...
Preparing to unpack .../4-linux-image-generic_4.18.0.15.16_amd64.deb ...
Unpacking linux-image-generic (4.18.0.15.16) over (4.18.0.14.15) ...
Selecting previously unselected package linux-headers-4.18.0-15.
Preparing to unpack .../5-linux-headers-4.18.0-15_4.18.0-15.16_all.deb ...
Unpacking linux-headers-4.18.0-15 (4.18.0-15.16) ...
Selecting previously unselected package linux-headers-4.18.0-15-generic.
Preparing to unpack .../6-linux-headers-4.18.0-15-generic_4.18.0-15.16_amd64.deb ...
Unpacking linux-headers-4.18.0-15-generic (4.18.0-15.16) ...
Preparing to unpack .../7-linux-headers-generic_4.18.0.15.16_amd64.deb ...
Unpacking linux-headers-generic (4.18.0.15.16) over (4.18.0.14.15) ...
Setting up linux-headers-4.18.0-15 (4.18.0-15.16) ...
Setting up linux-modules-4.18.0-15-generic (4.18.0-15.16) ...
Setting up linux-headers-4.18.0-15-generic (4.18.0-15.16) ...
Setting up linux-image-4.18.0-15-generic (4.18.0-15.16) ...
I: /vmlinuz.old is now a symlink to boot/vmlinuz-4.18.0-14-generic
I: /initrd.img.old is now a symlink to boot/initrd.img-4.18.0-14-generic
I: /vmlinuz is now a symlink to boot/vmlinuz-4.18.0-15-generic
I: /initrd.img is now a symlink to boot/initrd.img-4.18.0-15-generic
Setting up linux-modules-extra-4.18.0-15-generic (4.18.0-15.16) ...
Setting up linux-headers-generic (4.18.0.15.16) ...
Setting up linux-image-generic (4.18.0.15.16) ...
Setting up linux-generic (4.18.0.15.16) ...
Processing triggers for linux-image-4.18.0-15-generic (4.18.0-15.16) ...
/etc/kernel/postinst.d/initramfs-tools:
update-initramfs: Generating /boot/initrd.img-4.18.0-15-generic
I: The initramfs will attempt to resume from /dev/sda5
I: (UUID=09e25397-4a2c-4fb0-a605-a7013eecb59c)
I: Set the RESUME variable to override this.
/etc/kernel/postinst.d/zz-update-grub:
Sourcing file `/etc/default/grub'
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-4.18.0-15-generic
Found initrd image: /boot/initrd.img-4.18.0-15-generic
Found linux image: /boot/vmlinuz-4.18.0-14-generic
Found initrd image: /boot/initrd.img-4.18.0-14-generic
Found linux image: /boot/vmlinuz-4.18.0-13-generic
Found initrd image: /boot/initrd.img-4.18.0-13-generic
Found Windows Boot Manager on /dev/sda2@/EFI/Microsoft/Boot/bootmgfw.efi
Adding boot menu entry for EFI firmware configuration
done

3 Answers

The swap UUID needs to be added to the /etc/initramfs-tools/conf.d/resume file.

The following command can show what your swap UUID is:

blkid | awk -F\" '/swap/ {print $2}'

You can run the following to set that in the RESUME file (it will be created if it doesn't exist in that folder):

printf "RESUME=UUID=$(blkid | awk -F\" '/swap/ {print $2}')\n" | sudo tee /etc/initramfs-tools/conf.d/resume

Then run the following to update the kernels on the system:

sudo update-initramfs -u -k all

Reboot the system so the changes can take affect.

This does last through kernel updates.

Hope this helps!

I will add just one caveat.

The initramfs will attempt to resume from /dev/sda2
I: (UUID=139d357c-829d-408d-bccc-147ec4402da8)
I: Set the RESUME variable to override this.

The above was my case and the UUID stated there is the disk's (sda2 in my case) UUID, not the PARTUUID (i.e. the partition's UUID where the swap is installed).

This is so counter-intuitive, as the warning suggests, at least to me, that the disk's UUID was the problem!

But long story short, here is my solution:

Add the disk's UUID to the resume file not the partition's PARTUUID.

sudo gedit /etc/initramfs-tools/conf.d/resume

In my case I added:

RESUME=UUID=139d357c-829d-408d-bccc-147ec4402da8

And if this is not clear, my fstab for my swap location is:

/dev/sda2: UUID="139d357c-829d-408d-bccc-147ec4402da8" TYPE="swap"
PARTLABEL="HDD_Swap" PARTUUID="0067903b-aed0-48d1-8d59-956784616d48"

I use LVM (for swap too) on ubuntu server 20.04 and after installing updates I received the mentioned messages:

Processing triggers for initramfs-tools (0.136ubuntu6.3) ...
update-initramfs: Generating /boot/initrd.img->5.4.0-65->generic
I: The initramfs will attempt to resume from /dev/dm-2
I: (/dev/mapper/ubuntu--vg-ubusrv--lv--swap)
I: Set the RESUME variable to override this. 

I added RESUME=/dev/mapper/ubuntu--vg-ubusrv--lv--swap to a file resume under /etc/initramfs-tools/conf.d.

update initramfs worked without any "I's" shown