ORA-01466: unable to read data - table definition has changed

Checking at the errors, looks like some DDL changes are happening in the databases while export is running. On checking further at the error and looking at the LAST_DDL_TIME in some of the tables for which expdp failed,  the timestamp would be the exact time when export was running.

select object_name,subobject_name , object_type ,timestamp, last_ddl_time from dba_objects where object_name=;

In my case partitions (Object_Type =TABLE PARTITION)  got added in the tables when export was running which was a DDL change through some auto jobs setup for the same schema/tables for which we were taking the export.

To fix this issue don't create do any DDL changed in the database while export dump is in progress.