When in the Application Access screen, the following error shows for Bamboo:
Error communicating with Bamboo: Internal Server Error and users cannot be granted Application Access.

Workaround/Fix

1. Go to the Bamboo Global Permissions screen
2. Add your current user to the Global Permissions, and make it a limited-admin (this to make sure you don't lose Administrator access in the next step)
3. Save
4. Remove the Administrators-bamboo group from the Global Permissions (by unchecking all boxes)
5. Re-add the administrators-bamboo group to the Global Permissions as limited-admin

• Check the Application Access screen again.