Health Analyzer: The Security Token Service is not available – Sharepoint 2010 Error

Problem

You find the following entry in the SharePoint 2010 Central Administration Review problems and solutions All Reports listing:

And looking in the Windows Server Application log, you see the following error event occuring once every 15 minutes:

Log Name:      Application
Source:        Microsoft-SharePoint Products-SharePoint Foundation
Date:          [date/time]
Event ID:      8306
Task Category: Claims Authentication
Level:         Error
Keywords:     
User:          [domain\FarmServiceAccount]
Computer:      [NameOfFailingServer]
Description:
An exception occurred when trying to issue security token: Could not 
connect to 
http://localhost:[port]/SecurityTokenServiceApplication/securitytoken.svc/actas. 
TCP error code 10061: No connection could be made because the target 
machine actively refused it 127.0.0.1:[port]. .
Event Xml:

  
    
    8306
    14
    2
    47
    0
    0x4000000000000000
    
    29898
    
    
    Application
    [NameOfFailingServer]
    
  
  
    Could not connect to 
http://localhost:[port]/SecurityTokenServiceApplication/securitytoken.svc/actas. 
TCP error code 10061: No connection could be made because the target machine 
actively refused it 127.0.0.1:[port]. 
  

Solution

1. Solution A: Restart the Security Token Service application pool:
   1. As Administrator, launch IIS Manager.
   2. In the Connections pane (at left), expand the tree to view Application Pools.
   3. Select Application Pools.  This updates the results pane (center pane).
   4. Right-click on SecurityTokenServiceApplicationPool, and then click Stop.
   5. Right-click on SecurityTokenServiceApplicationPool, and then click Start.
   6. Go back to Central Administration, Review problems and solutions :All Reports view.
   7. Click on the issue, The Security Token Service is not available.
   8. Click Re-analyze Now.
   9. Click Close.
   10. Refresh after several minutes.
2. Solution B: Re-provision the service
   1. Launch the SharePoint Management Shell as Administrator.
   2. Run the following script:

      $sts = Get-SPServiceApplication | ?{$_ -match "Security"}
      $sts.Status
      $sts.Provision()​
      

   3. Go back to Central Administration, Review problems and solutions :All Reports view.
   4. Click on the issue, The Security Token Service is not available.
   5. Click Re-analyze Now.
   6. Click Close.
   7. Refresh after several minutes.