Why Plesk reports that system updates are available after installing them manually via apt or yum command?

Question

Why does Plesk still report that there are pending System Updates in the Tools & Settings > System Updates menu, after they were installed with the apt or yum package manager?

Answer

The information in the Tools & Settings > System Updates is not updated on the go. It is cached until one of the following events occurs:

1. The Check for Updates button is clicked in the Tools & Settings > System Updates menu or on the Websites & Domains page.
2. The system updates are being installed via Plesk > Tools & Settings > System Updates > Install
3. Plesk is being updated to the next version from the Tools & Settings > Updates menu or when using the plesk installer command.

When updates are installed manually using the apt or yum package manager, the information in the System Updates menu remains the same. None of the actions above are performed, so Plesk does not reset this "cache" as it is not aware of it at the moment.

If you install OS updates with the native apt or yum command, to update the information regarding system packages in Plesk, it is required to additionally click on the Check for Updates button in the Plesk GUI.

Alternatively, you could simply wait 24 hours for the next Plesk Daily Maintenance task to run and the cache will be cleared automatically.