Steps
The message Parameters successfully updated will display and the Classes menu option will appear within the Administration Menu when the update is complete.
Only users with Sys Admin permissions can activate Classes within your system.
Go to Administration > System > System Settings > Features
Scroll down to the Issue Classes section.
Select Activate Issue Classes.
Enter a Default Class for your system's issues. (This value will only be used when a submitter cannot or does not specifically select one.)
The value entered here must also be added as a Class to your system.
Click Update
The message Parameters successfully updated will display and the Classes menu option will appear within the Administration Menu when the update is complete.