All Oracle Error CodesOracle DBA Forum

ORA-28575:

unable to open RPC connection to external procedure agent
Cause: Initialization of a network connection to the extproc agent did not succeed. This problem can be caused by network problems, incorrect listener configuration, or incorrect transfer code.
Action: Check listener configuration in LISTENER.ORA and TNSNAMES.ORA, or check Oracle Names Server.
 SubjectReplies
1.External Procedures and Linux1