Yes, ther reason there is a restriction on dataPump export. It cannot export schemas like SYS, ORDSYS, EXFSYS, MDSYS, DMSYS, CTXSYS, ORDPLUGINS, LBACSYS, XDB, SI_INFORMTN_SCHEMA, DIP, DBSNMP and WMSYS in any mode.
Please also check
EXP-10 Usernames Which Cannot Be Exported (Doc ID 217135.1)
DataPump Export (EXPDP) Fails With Error ORA-39165 Schema SYS Was Not Found (Doc ID 553402.1)
Any further help is most welcome.
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