Running AdminUI, and trying to export Metadata from Federation Entity, the AdminUI reports the error:
Error: Unexpected system error trying to export metadata: null
This issue occurs by following these steps:
Policy Server 12.8SP8CR0 on RedHat 7;
AdminUI 12.8SP8CR0 on RedHat 7;
Policy Store on CA Directory 14.1SP4;
Upgrade the AdminUI to 12.8SP8CR01 to benefit from fix DE591739 and solve this issue.
Remember: to run AdminUI 12.8SP8CR01, upgrade also the Policy Server and the Policy Store definitions to 12.8SP8CR01 too.