Upgrading Drupal

I was unable to uninstall drupal/content_scroller in D8.9.6 using the GUI:

Error: Call to undefined function variable_del() in content_scroller_uninstall() (line 12 of modules/contrib/content_scroller/content_scroller.install).

When I update the site to D9.0.6, I get errors updating the db saying the module is missing (I removed it). If I copy it back from the D8 installation, I get

I am trying to upgrade from drupal 8.9.2 to drupal 9
First checked al modules that are not 9.0 ready and removed them
Then i did this command:
composer require drupal/core-recommended:^9.0.0 drupal/core-composer-scaffold:^9.0.0 drupal/core-project-message:^9.0.0 --update-with-dependencies --no-update

This was ready very quick and only gives that composer.json was updated.

Then 
composer update

This gives a long list with at start this:

I strongly need any hint after updating Drupal core.

I did the critical core update from 7.59 do 7.72. After that I'm experiencing some strange problems. I assume they are somehow connected to Bootstrap and/or Javascript. I have used Bootstrap as a fundation of my custom theme. So, after the core update I noticed that different elements of my website stopped working - the dropdown menu doesn't work, the bootstrap carousel (that I used in a view) has stopped and it doesn't work even though I have the navigation "showed".

Hi I'm trying to update a drupal install from 9.0.3 to 9.0.6 its throwing an exception during the composer update Its installed on Ubuntu 18.04

I've run 
composer update drupal/core-recommended --with-dependencies

I'm getting the following output

I am trying to Update Drupal 8 from 8.6.14 to latest 8.9.6, when changing Core & Vendor folder for new ones, geting blank white screen; Modules are also versions around 1-2 years old;

At one point I was getting some warning that my Pathauto version 1.4 is too old, but how can I update Pathauto, if New Versions Drupal doesn't work with old Pathauto?! - and New Pathauto doesn't work with Old Drupal?!

Also, I am now reading Logs, not that I understand something there....

Error Logs gives many errors or 2 kinds, while I was switching core / new & core old:

I have two installs of D9 on VPS(Debian/Nginx) -> The first is a update from latest D8 to D9 and the second is a empty D9. What is the difference?

The empty version in report shows -> 9.0.6 and in wappalyzer Drupal 9 - I think everything is ok.

The updated version in report shows -> 9.0.6 but in wappalyzer still Drupal 8. Additionally all my contents in list (admin/content) shows with permamently red hints "NEW". Now I know that the new empty instance it is right solution but in my case I have too much contents, views, codes etc. Its not easy.