Symptoms

When accessing the issue and directly accessing the comment tab, the umlaut characters will appear fine. However, navigating to Comment tab -> History tab -> Comment tab will break the umlaut character

Diagnosis

• All configuration is using UTF-8  
• check if third-party plugin called JIRA Field Security plugin is installed
•  Enabling Safe Mode fix the problem

Cause

Field Security plugin caused the umlaut character to break.

Resolution

• Disabled the JIRA Field Security plugin