Issue
We are using 'Email Extension Plugin' for email notifications. As you can see from the attached screenshot, Jenkins throws an exception when we click on 'Email Template Testing' and 'Log in' link appears on right upper screen even though we are still logged in.
Resolution
In this case, the installation was corrupt. Uninstalling and reinstalling the plugin resolved the issue.
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.