Oracle Message ORA-14284 - one or more of tables subpartitions reside in a read-only tablespace

ERRORone or more of tables subpartitions reside in a read-only tablespace
CAUSEUser issued ALTER TABLE statement attempting to modify an existing VARCHAR2 (or VARCHAR) column to be of type CHAR (or CHARACTER), increase length of an existing CHAR (or CHARACTER) column, or add a column with user-specified default for a table one or more subpartitions of which reside in read-only tablespaces, which is illegal
ACTIONAvoid performing aformentioned operations on a partitioned table one or more subpartitions of which reside in read-only tablespaces