How to fix N: This must be accepted explicitly before updates for this repository can be applied in APT

The quickest solution is to run apt-get update with the --allow-releaseinfo-change flag:

sudo apt-get update --allow-releaseinfo-change

This command explicitly accepts the changed repository metadata and proceeds with the update. Run it once, and subsequent apt-get update commands will work normally.

For a more interactive approach, use the apt command instead of apt-get:

sudo apt update

The apt command will prompt you with "Do you want to accept these changes and continue updating from this repository? [y/N]". Type "y" and press Enter to accept the changes. This is the preferred method for interactive use in recent Ubuntu versions.

If you want to permanently accept all release information changes, add this line to your APT configuration:

sudo nano /etc/apt/apt.conf.d/99-allow-release-changes

Add the following content:

Acquire::AllowReleaseInfoChange::Suite "true";

Save and exit (Ctrl+X, then Y, then Enter). This configuration allows suite changes without requiring the flag each time. Use with caution and only if you understand the implications.

After accepting the release changes, verify that package updates work correctly:

sudo apt-get update
sudo apt-get upgrade

You should no longer see the "This must be accepted explicitly" error. The upgrade command shows you what packages will be updated before proceeding.