So yesterday I've upgraded to Ubuntu 20.04 from 18.04, firstly I had to finish up with a partial upgrade that the software updater suggested, then it asked me to remove all the unused packages so I did, then I've ran it one more time to be sure ALL the software is up to date, it seemed at first glance it went well.
Today I found out there are no applications in the "start" menu (when you click on the Ubuntu icon on the launcher, some may call it applications lens) - I only got a message "Sorry, there is nothing that matches your search" application menu gone too with same message.

I did search a bit but I found a similar problem only for gnome caused by gnome-tweaks tool, but I am using Unity, but in the end...

...I found the solution - see steps in my answer :)

While I am growing to be more and more fond of Unity, there are a few minor things I'd like to change. One of them in which is the default view of the dash. When I go into the dash, 99% of the time it's after an application.

I'd REALLY like to find a way to have the Applications lens be the default one. Is this possible in any way? I just find it cumbersome to click the dash icon, bottom of the dash select the 2nd icon (applications lens) then select "see more results" to see all of them.

I apologize in advance if I am leaving something out here. Please let me know what additional info is required, and i will be happy to post it.

Can you tell me what these error messages are, and how I can go about resolving them?

WARN  2012-02-02 14:02:56 unity.glib.dbusproxy GLibDBusProxy.cpp:255 Cannot call method InfoRequest proxy /net/launchpad/lens/utilities does not exist
WARN  2012-02-02 14:02:56 unity.glib.dbusproxy GLibDBusProxy.cpp:255 Cannot call method SetActive proxy /net/launchpad/lens/utilities does not exist
WARN  2012-02-02 14:02:56 unity.iconloader IconLoader.cpp:509 Unable to load contents of file:///usr/share/icons/unity-icon-theme/places/svg/category-installed.svg: Error opening file: No such file or directory
WARN  2012-02-02 14:02:56 unity.iconloader IconLoader.cpp:509 Unable to load contents of file:///usr/share/icons/unity-icon-theme/places/svg/category-available.svg: Error opening file: No such file or directory
WARN  2012-02-02 14:02:56 unity.glib.dbusproxy GLibDBusProxy.cpp:255 Cannot call method InfoRequest proxy /net/launchpad/lens/askubuntu does not exist
WARN  2012-02-02 14:02:56 unity.glib.dbusproxy GLibDBusProxy.cpp:255 Cannot call method SetActive proxy /net/launchpad/lens/askubuntu does not exist

I am also getting Nautilus errors logged here. I do not remember what lenses I installed, or from where (Software Center, manual install, etc).