max@max-Vostro-5568:~/Desktop$ sudo apt upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
You might want to run 'apt --fix-broken install' to correct these.
The following packages have unmet dependencies:
snapd : Breaks: apt (< 1.6.3) but 1.6.1 is installed
E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution).
Further I try to eliminate these problems, but self-removal occurs.
max@max-Vostro-5568:~/Desktop$ sudo apt install -f
Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following packages were automatically installed and are no longer required:
libapt-inst1.5 libapt-pkg4.12 linux-headers-5.3.0-28
linux-headers-5.3.0-28-generic linux-image-5.3.0-28-generic
linux-modules-5.3.0-28-generic linux-modules-extra-5.3.0-28-generic
python3-debconf
Use 'sudo apt autoremove' to remove them.
The following packages will be REMOVED:
apt
WARNING: The following essential packages will be removed.
This should NOT be done unless you know exactly what you are doing!
apt
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 3,896 kB disk space will be freed.
You are about to do something potentially harmful.
To continue type in the phrase 'Yes, do as I say!'
?] Yes, do as I say!
(Reading database ... 223329 files and directories currently installed.)
Removing apt (1.6.1) ...
Processing triggers for man-db (2.8.3-2ubuntu0.1) ...
Processing triggers for libc-bin (2.27-3ubuntu1) ...
max@max-Vostro-5568:~/Desktop$ apt
bash: /usr/bin/apt: No such file or directory
sudo apt update
. Looks like possible mixed-version sources. – user535733 Apr 23 '20 at 18:22