Upgrading Drupal

Hi all,

Thanks for looking into this topic.

Since I upgraded my Drupal core I got this error message when I want to upload images for example:
The specified file temporary://filebCn7yX could not be copied, because the destination directory is not properly configured. This may be caused by a problem with file or directory permissions. More information is available in the system log.

I already checked the file system paths and they're set on:
sites/default/files
Also the tmp directory is set correctly as the files are going in as I can see.

Get a 500 error when trying to edit a page after upgrading to drupal 9.4.1 from 8.9.19 log shows error:

Drupal\Component\Plugin\Exception\PluginException: Plugin (linkit) instance class "Drupal\linkit\Plugin\CKEditorPlugin\Linkit_08-11-22_10-23-02" does not exist. in Drupal\Component\Plugin\Factory\DefaultFactory::getPluginClass() (line 97 of C:\inetpub\drupal\core\lib\Drupal\Component\Plugin\Factory\DefaultFactory.php).

I'm upgrading from D7 to D9 on a local Windows ddev/docker setup.

Using Migrate Drupal UI:

When I run the upgrade review, I get the confirmation page with the warning about my contest being overwritten, but when I click to continue, I get a blank screen with "The website encountered an unexpected error. Please try again later."

When I check in my dlog, I see the following error. The Referrer is https:/mysite.ddev.site/upgrade/idconflict

Hi, 
We are on Drupal core 9.4.7, and all our modules have been uptodate except the drupal/admin_toolbar.

Hello,
Upgrading to Drupal 9.4.7 I found that the following code doesn't work anymore:

Steps to reproduce, configure webform module to upload a file to a private directory. Upload file. Try and access that file as a user other than user #1. Access denied.

Reverting to Drupal version 7.91 resolved the issue.

I am unable to determine the root cause.