Issue

• I see a warning saying “You have data stored in an older format and/or unreadable data.” with two buttons “Manage” and “Dismiss”, and/or “It is acceptable to leave unreadable data in these files, as Jenkins will safely ignore it.”

Environment

• CloudBees CI (CloudBees Core)
• CloudBees CI (CloudBees Core) on modern cloud platforms - Managed Master
• CloudBees CI (CloudBees Core) on modern cloud platforms - Operations Center
• CloudBees CI (CloudBees Core) on traditional platforms - Client Master
• CloudBees CI (CloudBees Core) on traditional platforms - Operations Center
• CloudBees Jenkins Enterprise
• CloudBees Jenkins Enterprise - Managed Master
• CloudBees Jenkins Enterprise - Operations Center
• CloudBees Jenkins Platform - Client Master
• CloudBees Jenkins Platform - Operations Center
• CloudBees Jenkins Distribution
• CloudBees Jenkins X Distribution
• Jenkins LTS

Resolution

In most cases, these messages can be dismissed. This can occur when you configure a plugin, and later disable it.
There are jobs using the disabled plugin’s functionality, and the data is still in config.xml but has no purpose without the plugin.

Selecting the “Dismiss” button may be appropriate if the plugin was temporarily disabled, or is intended to be used again in the future.

If you click the “Manage” button, you will be able to delete the keys that have no purpose in the current context - in the config.xml for each of the listed jobs.