Oracle Message ORA-14266 - data type or length of an index subpartitioning column may not be changed

ERRORdata type or length of an index subpartitioning column may not be changed
CAUSEUser issued ALTER TABLE statement attempting to modify data type and/or length of a column used to subpartition some index defined on the table named in ALTER TABLE statement, which is illegal
ACTIONAvoid modifying data type and/or length of index subpartitioning column(s)