Upgrading Drupal

I laboriously updated all my modules to pass the update status tests, and followed the steps at https://www.drupal.org/docs/upgrading-drupal/upgrading-from-drupal-8-or-...

But when I do composer update, I get

I have created a virtual appliance that runs Drupal.  I cannot provide access to the appliance console but I would like to be able to update the Drupal site with new features and fix patches. 

Hosting software upgrades and patches is not a problem.  Creating them and applying them is where I need a better understanding please. 

Thanks for your time and thoughts.

I try to upgrade Drupal 8.9.20 to Drupal 9.0.0, I used upgrade status. 100% of my project is compatible with 9.0.

During the drush command updatedb, this error appears :

 Do you wish to run the specified pending updates? (yes/no) [yes]:
 > yes

While performing a minor upgrade to  version 7.94, I got stuck  details are here convert MySQL issue. How do I move past the requirements verification step of the update script?

Hello community,

a list of modules available at /admin/modules shows only modules of 'core' section. An information
"Enable the Update Manager module to update and install modules and themes." is displayed at /admin/modules but "update manager module" can not be activated because it is not listed in core modules.

At the same time list of modules suitable for deinstall operation available at /admin/modules/uninstall is full with all the custom modules installed so far by me.

An example:

After updating a site running 7.92 fro PHP 7.4 to PHP 8.1, the site crashes with 'Unexpected error'.

The log show the following

mod_fcgid: stderr: PHP Deprecated:  Optional parameter $feed_nid declared before required parameter $context is implicitly treated as a required parameter in /home/domains/vol3/162/1262162/user/htdocs/sites/all/modules/feeds/feeds.module on line 272,

Could someone please explain this?