In Sharepoint 2010, User Profile Service Application is a new service that replaced the SSP. I encountered ""An unexpected error has occurred." error when I selected a user and click on Edit, and also when I wanted to edit User Profile Properties. The page was working correctly without any problems previously. Due to some unknown reasons, the user profile service application failed and was throwing me this error page.
This is an expected behaviour if the User Profile Synchronization Service is started on the SharePoint server hosting Central Administration. To fix this issue, simply perform a recycle of IIS Central Administration Application pool is required to get this working.
