3589949 - IRJ Portal Runtime error when SSO via Logon Tickets is configured

Portal iViews are set to use login tickets for backend system authentication.
When trying to open iViews (reports) in the portal, users encounter the following error:

"Portal runtime error 
An exception occurred while processing your request. Send the exception ID to your portal administrator.
[...]"

When checking the traces, the following errors are encountered: 

"[...] Creating assertion ticket failed for an unknown reason.
[EXCEPTION]
java.security.PrivilegedActionException: com.sap.security.api.umap.NoLogonDataAvailableException: Ticket generation failed."

"[...][EXCEPTION]
com.sapportals.portal.appintegrator.ApplicationIntegratorException: com.sap.security.api.umap.NoLogonDataAvailableException: Creating assertion ticket failed for an unknown reason."

"[...] Certificate under alias [SAPLogonTicketKeypair] cannot be retrieved from keystore view [TicketKeystore]. Authentication stack: [XXXXXXXXXX]."

"[...][EXCEPTION]
java.lang.Exception: Cannot read certificate from keystore."

The Authentication Stack has the default configuration: 

         Module                                                  Flag

EvaluateTicketloginModule                         SUFFICIENT
BasicPasswordloginModule                         REQUISITE
CreateTicketLoginModule                           OPTIONAL

• SAP NetWeaver
• SAP NetWeaver Application Server for Java
• SAP NetWeaver Enterprise Portal

Portal runtime error,  Ticket generation failed, Creating assertion ticket failed for an unknown reason, Certificate under alias [SAPLogonTicketKeypair] cannot be retrieved from keystore view [TicketKeystore], Cannot read certificate from keystore, NoLogonDataAvailableException, iViews, Java , KBA , BC-JAS-SEC , Security, User Management , EP-PIN-AI , Application Integration , BC-JAS-SEC-LGN , Logon, SSO , Problem