create or replace table t1 (x int)

partition by range columns (x) (

  partition p0 values less than (10),

  partition p1 values less than (20),

  partition pn values less than maxvalue);

insert into t1 values (21);

alter table t1 convert partition pn to table pn;

alter table t1 add partition (partition p2 values less than (30));

alter table t1 convert table pn to partition pn values less than maxvalue;

alter table t1 convert table pn to partition pn values less than maxvalue;

ERROR 1737 (HY000): Found a row that does not match the partition