Upgrading Drupal

I've attempted an upgrade from 9.29 to 9.30, and the upgrade goes fine. The 8 database updates also apply without issue, however when i browse to the site, i get :

The website encountered an unexpected error. Please try again later.

and the error in the event log is :
 

Please disregard this post as it was not a core problem, it was a contributed module error. 

Had a very unpleasant surprise last night when upgrading Drupal 9.3.0 to 9.3.2

Composer detected issues in your platform: Your Composer dependencies require a PHP version ">= 7.4.0".

I had version PHP Version 7.3.33

General panic ensued.

Hello,

I just update d8 to d9 and I can't update data of modules.

I have this message :

Failed to fetch available update data:

I've already upgraded a couple of my sites to D9 without many problems, but one is not allowing me to finish updates before moving to D9.

I have tried doing "drush updatedb" as well as the update database link on the site. Both fail and I get this error:

Error: Undefined class constant 'INSECURE_EXTENSION_REGEX' in {closure}() (line 32 of /var/www/vhosts/mysite.com/newsite/web/core/modules/file/file.post_update.php)

in the https://www.drupal.org/docs/7/upgrade-to-drupal-7/drupal-6-contributed-modules-that-are-in-drupal-7-core page, under "Modules that can be uninstalled from your D6 site prior to upgrade" list, the modules autoload, imageapi, jquery_ui, simpletest all have D7 version.

ERROR:

In Process.php line 335:

  fopen(/home/tonigonz/www/vendor/symfony/process/Process.php): Failed to open stream: No such file or directory

Hello,

I use composer to update my website from 9.2.10 to 9.3. First in my local WAMP host, it wasn't any problem. Everything was correctly updated.

When I tried to update it in my shared production hosting, the composer message was as follow: