I just installed Kali Linux (on /dev/sda5) in dual boot with Ubuntu (on /dev/sda2). However, now that I have Kali, Ubuntu takes a few minutes to launch, whereas Kali takes a few seconds, and I would like the contrary. How can I do that ?

EDIT 1

• Ubuntu took about 20 seconds to launch before I installed the dual boot.


• I have updated Grub on both partitions, so it looks different if I choose to boot with Ubuntu or Kali in the BIOS.


• The step that seems to take the more time (about two thirds of the time) shows :
  a start job is running for dev-disk-by...a-lot-of-characters....device
  

EDIT 2

Editing my fstab to have the correct UUID for my swap partition only reduced by half the booting time: Ubuntu still takes a good 45 seconds to launch: so my question is not a duplicate of the questions suggested.

EDIT 3

Rebuilding my initramfs (sudo update-initramfs -u) and then updating grub (sudo update-grub) did the job: now Ubuntu takes only 10 seconds to launch. Thanks everyone!

(I would have rather posted a comment asking for more information, but I can't, so...)

You probably change some of your partitions during the installation process and now your system is trying to mount a partition that no longer exists, or some other impossible thing, until the job finally timeouts and gives up You should edit your /etc/fstab according to your current partitions, that you can check in a variety of ways(fdisk, lsblk, etc).

This question looks very similar to yours and may be exactly your problem(since your system boots, it wasn't a very important partition that failed, maybe swap?).

In this question they even suggest gparted, which has a graphical interface, to check partitions if you prefer.