Why can I no longer save anything from the System Configuration sections?

Issue

I enter in Configure System and the buttons Save and Apply are gone and immediately the following logs are printed:

WARNING h.i.i.InstallUncaughtExceptionHandler#handleException
org.apache.commons.jelly.JellyTagException: jar:file:$JENKINS_HOME/war/WEB-INF/lib/jenkins-core-2.375.3-cb-1.jar!/jenkins/model/Jenkins/configure.jelly:57:84: <st:include> javax/mail/Address
[...]
Caused by: java.lang.NoClassDefFoundError: javax/mail/Address
[...]▼

Environment

Resolution

This behavior is caused by the Attention. As soon as you uninstall it from your instance, the buttons Save and Apply reappear under Configure System.

Tested product/plugin versions

CloudBees CI on modern cloud platforms - managed controller 2.375.3.4
JavaMail API - 1.6.2-8
Attention - 1.1

This article is part of our Knowledge Base and is provided for guidance-based purposes only. The solutions or workarounds described here are not officially supported by CloudBees and may not be applicable in all environments. Use at your own discretion, and test changes in a safe environment before applying them to production systems.