Had this problem on all my SharePoint 2010 site.

[sourcecode]
[NullReferenceException: Object reference not set to an instance of an object.]
Microsoft.Office.Server.Administration.UserProfileApplicationProxy.get_ApplicationProperties() +134
Microsoft.Office.Server.Administration.UserProfileApplicationProxy.get_PartitionIDs() +44
Microsoft.Office.Server.Administration.UserProfileApplicationProxy.IsAvailable(SPServiceContext serviceContext) +329
Microsoft.Office.Server.WebControls.MyLinksRibbon.get_PortalAvailable() +44
Microsoft.Office.Server.WebControls.MyLinksRibbon.EnsureMySiteUrls() +60
Microsoft.Office.Server.WebControls.MyLinksRibbon.get_PortalMySiteUrlAvailable() +15
Microsoft.Office.Server.WebControls.MyLinksRibbon.OnLoad(EventArgs e) +91
System.Web.UI.Control.LoadRecursive() +65
System.Web.UI.Control.LoadRecursive() +190
System.Web.UI.Control.LoadRecursive() +190
System.Web.UI.Control.LoadRecursive() +190
System.Web.UI.Control.LoadRecursive() +190
System.Web.UI.Control.LoadRecursive() +190
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2427
[/sourcecode]

Checked Event Viewer for the log. Event: 8306 SharePoint Foundation error thrown

[sourcecode]
An exception occurred when trying to issue security token: Could not connect to http://localhost:32843/SecurityTokenServiceApplication/securitytoken.svc/actas. TCP error code 10061: No connection could be made because the target machine actively refused it 127.0.0.1:32843. .</span>
[/sourcecode]

Tried the following steps (not working)

1. Stopped the User profile sync service
2. Stopped user profile service application
3. Recycled SecurityTokenServiceAppPool with re-typing credentials
4. Started User Profile service
5. Started Sync service

Resolution

1. Go to IIS (Internet Information Services) Manager
2. Turn on “SharePoint Web Services Root” Application Pool
3. Turn on “SharePoint Web Services” sites
4. run iisreset via cmd

Worked!