Starting on 19 October 2021 (18:31:36 GMT), you may see an error message on the Plugin Management page on your CloudBees CI instances. This error has no impact on the operational status of your instance; all of your builds will run as usual. However, this could impact you when creating new controllers for both online and air-gapped environments.
Release 2.303.2.6 enables plugin installation and updates for instances in air-gapped environments, removes the error from the Plugin Management page, and corrects plugin installation during new controller provisioning for online and air-gapped environments.
Please refer to the following KB article for more information and workarounds: