Oracle Message ORA-16006 - audit_trail destination incompatible with database open mode

ERRORaudit_trail destination incompatible with database open mode
CAUSEThe audit_trail initialization parameter was set to DB (or TRUE), which is incompatible with a database opened for read-only access.
ACTIONWhen the database is opened for read-only access, the audit_trail initialization parameter can only be set to OS or NONE (FALSE).