The certificate used to encrypt and sign SAML assertions for appcenterhq.com tenants expires on 3/6/14.  This certificate is being replaced on 1/30/2014, simultaneously with the App Center 4.3.1 release.

The original certificate will function with SAML configurations until the original certificate expires in March. Prior to that, customers currently configured with the SAML external IDP require a reconfiguration to use the new certificate.  Failure to update your SAML provider will result in the inability for users to authenticate.

To perform the reconfiguration, do the following:  

1.  Download a new copy of the App Center SP Metadata File on the Settings > External Identity Provider/Server Configuration page.

2.  Reconfigure the SAML provider using the new copy of the SP Metadata File.