SharePoint 2010 - You must have manage user profiles administrator rights to use administrator mode.

Goal

As the error metions the user should be "Admin in User Profile Service". The error comes when a user try to update a profile(other user's profile). Please read my last blog for more clarification SharePoint 2010 - Update user's infomation using UserProfileManager programmatically.

Fix

• SharePoint 2010 Central Administration
• Application Management > Manage Service Applications
• Select the "User Profile Service Application" tab. On the top you can find an option of "Administrators".
  
  
• Apply the user you are using in the Administrators and give rights to the user. I am using "Administrator" as a user.
  
  
Let me know if this is helpfull.