Problem Definition

Sometimes a System App, or a module of a System App, might be disabled while Confluence is running or during startup. This could happen by a bug on Confluence or modified directly from the database.
A Confluence administrator isn't able to enable this App/Module from the Universal Plugin Manager UI, requiring some downtime to restart the application when the problem is identified.

Note that this enhancement is not targeted on being able to disable these Apps/modules, but solely on the ability to enable them.

Suggested Solution

When a System App (or module of a system app) is disabled, give the Confluence Administrator the ability to enable it from the UPM UI.

Workarounds

Use UPM REST API

Call UPM REST API to change the status of a given plugin or a single module

• UPM REST API

Directly updating the database

Enable the App or the module via data manipulation on the database.
Refer to the following KB articles on how to accomplish it:

• How to Manually Change a Plugin Back to Default State Through the Database
• How to reset all Confluence plugins back to their default state through the database
• How Do I find enabled and disabled plugins in the database?