I face with this error message during export,import process in scheduled crontab job.

Source and Target DB versions are both and OS are AIX 7.1

After investigate issue We noticed, you can face this error because of 2 reasons.

1. The XML feature is not installed. Because we are attempting to invoke XML/XDB features during the import, the error is raised.

You need to Query view dba_registry to check if XDB and XML components are installed and valid on both source and target databases:

select comp_id,comp_name,version,status from dba_registry;

If you need to install XML feature you can use this note:
Master Note for Oracle XML Database (XDB) Install / Deinstall [ID 1292089.1]
Data Pump Import Fails With ORA-942 ORA-06512 And ORA-38500 [ID 1350414.1]

2. If the involved table is a standard table and does not use XML DB. So why is the XML DB error reported?

The issue is generated when tables have differences.The error is happening due to the metadata differences of the exported table in the dumpfile and the existing table in the target DB.

In general, whenever there is a difference between metadata of a table from a dumpfile and a pre-existing table in a target DB, the IMPDP code tries to find the difference between the metadata of the table to find the correct metadata. To find the metadata difference, we use metadata code which internally uses the XDB feature to differentiate metadata XML.

If you repeat export&import process than  the DataPump import will be succeeded.

For more details you can refer this note:
Ora-38500 Raised By IMPDP For Table That Does Not Use XML DB (Doc ID 1424643.1)