For Cloudron users the biggest issue will be the following:

This change affects instances previously using features that now require a license, including:

• SSO — SSO login will no longer work. Users who authenticate through SSO will be unable to log in and must be converted to email and password users to regain access.

We advise applying for an "Open Innovation Grant" licence here: https://directus.com/oig if you are eligible for it.
With such a licence you can fully migrate to Directus v12 without losing any features and functions.

Option 1: Setting the licence in the /app/data/env.sh file

Open the Web File Manager of your @directus app and add the following line:

export LICENSE_KEY="YOUR_LICENSE_KEY"

Restart your @directus app.

Option 2: Admin facing modal for migration

After updating @directus to version v12 you get greeted with the following view:

Press the Continue button.

This view gives the option to either manage your licence or disable SSO.
Press the Manage License button:

Following that, press the Add License button:

Enter your licence key (1) and press save (2):