The published Knowledge Document(KD) does not appear in the Knowledge tab at all. The Knowledge tab's right pane shows the following error.
AHD10907 : Internal error. Please request assistance from system admin.
The Knowledge category shows up the published KDs without any problem. The Sharepoint's site search shows up the KD content.
SDM r14.1 Cum2 / Federated Search (Sharepoint) / Oracle for mdb database.
The Oracle's system/mdbadmin users' password was expired during the SDM service was running.
After re-setting the password of the system and mdbadmin users on Oracle, run pdm_configure. After that, the problem will solve.