title: Azure ACS - ACS20001 exception while login using SiteMinder IDP
body: <p>I have created a sample 'Windows Azure cloud service' project in visual studio 2010 and configured AZURE ACS as STS for this application using WIF for .NET 4.0. then deployed this application in Windows Azure Cloud Services. I configured Windows Live ID, Yahoo (out of box) and SiteMinder 12.51 as Identity Providers. Now, I am able to login to application using Yahoo and Windows Live ID identity providers.</p>
  
  <p>My RP in ACS (Windows azure cloud service application) accepts SAML 2.0 tokens. I have configured WS-FED SAML 2.0 federation between Azure ACS and SiteMinder 12.51. I have valid certs for Token Encryption, Decryption and Signing in ACS. I have configured SiteMinder IDP using MetaData import and ACS realm showing correct entity url. While login to application through SiteMinder (as IDP in ACS) I am getting below error.</p>
  
  <p>An error occurred while processing your request. </p>
  
  <pre><code>HTTP Error Code:    400 
  Message:    ACS20001: An error occurred while processing a WS-Federation sign-in response. 
  Trace ID:   3881b53c-e964-46c6-9f82-0fff383db6d5 
  Timestamp:  2013-05-15 11:22:39Z 
  </code></pre>
  
  <p>Here I don't see 'Inner Message'  for my exception. What are all the possible causes in my case? How can I enable inner message in ACS.
  I would greatly appreciate, If anyone help me on this issue. </p>
  
  <p>Thanks,
  Mahesh</p>