Assertion `field->type.mbminlen == 1' failed in row_merge_buf_redundant_convert

--source include/have_innodb.inc

CREATE TABLE t1 (id INT PRIMARY KEY, a CHAR(8), b CHAR(8) AS (a) VIRTUAL, KEY(b(3))) CHARACTER SET utf16 ENGINE=InnoDB;

INSERT INTO t1 (id,a) VALUES (1,'foo'),(2,'bar');

ALTER TABLE t1 ROW_FORMAT=REDUNDANT;

# Cleanup

DROP TABLE t1;

mysqld: /data/src/10.2/storage/innobase/row/row0merge.cc:443: void row_merge_buf_redundant_convert(const dfield_t*, dfield_t*, ulint, const page_size_t&, mem_heap_t*): Assertion `field->type.mbminlen == 1' failed.

210202 14:24:08 [ERROR] mysqld got signal 6 ;

#7  0x00007f53c5bb6f36 in __GI___assert_fail (assertion=0x55a11e41c151 "field->type.mbminlen == 1", file=0x55a11e41bee8 "/data/src/10.2/storage/innobase/row/row0merge.cc", line=443, function=0x55a11e41c0e8 "void row_merge_buf_redundant_convert(const dfield_t*, dfield_t*, ulint, const page_size_t&, mem_heap_t*)") at assert.c:101

#8  0x000055a11ddd5176 in row_merge_buf_redundant_convert (row_field=0x7f536803abf0, field=0x7f53680a49e0, len=32, page_size=..., heap=0x7f536804ab30) at /data/src/10.2/storage/innobase/row/row0merge.cc:443

#9  0x000055a11ddd5d16 in row_merge_buf_add (buf=0x7f53680a4920, fts_index=0x0, old_table=0x7f5368173370, new_table=0x7f53680a10f0, psort_info=0x0, row=0x7f536803ab40, ext=0x0, doc_id=0x7f53bbfafeb8, conv_heap=0x7f536804ab30, err=0x7f53bbfafea4, v_heap=0x7f53bbfafeb0, my_table=0x7f536809e960, trx=0x7f53c0bef120) at /data/src/10.2/storage/innobase/row/row0merge.cc:696

#10 0x000055a11dddaa6b in row_merge_read_clustered_index (trx=0x7f53c0bef120, table=0x7f536809e960, old_table=0x7f5368173370, new_table=0x7f53680a10f0, online=false, index=0x7f53680a0ee0, fts_sort_idx=0x0, psort_info=0x0, files=0x7f536816e420, key_numbers=0x7f53680a0ef0, n_index=2, add_cols=0x0, add_v=0x0, col_map=0x7f53680a0f28, add_autoinc=18446744073709551615, sequence=..., block=0x7f53b80f3000 "", skip_pk_sort=true, tmpfd=0x7f53bbfb0988, stage=0x7f53680349a0, pct_cost=33.333333333333336, crypt_block=0x0, eval_table=0x7f536809e960) at /data/src/10.2/storage/innobase/row/row0merge.cc:2231

#11 0x000055a11dde13b2 in row_merge_build_indexes (trx=0x7f53c0bef120, old_table=0x7f5368173370, new_table=0x7f53680a10f0, online=false, indexes=0x7f53680a0ee0, key_numbers=0x7f53680a0ef0, n_indexes=2, table=0x7f536809e960, add_cols=0x0, col_map=0x7f53680a0f28, add_autoinc=18446744073709551615, sequence=..., skip_pk_sort=true, stage=0x7f53680349a0, add_v=0x0, eval_table=0x7f536809e960) at /data/src/10.2/storage/innobase/row/row0merge.cc:4681

#12 0x000055a11dce8427 in ha_innobase::inplace_alter_table (this=0x7f53680ab1a8, altered_table=0x7f536809e960, ha_alter_info=0x7f53bbfb1030) at /data/src/10.2/storage/innobase/handler/handler0alter.cc:6292

#13 0x000055a11d8fc4a1 in handler::ha_inplace_alter_table (this=0x7f53680ab1a8, altered_table=0x7f536809e960, ha_alter_info=0x7f53bbfb1030) at /data/src/10.2/sql/handler.h:3792

#14 0x000055a11d8f1931 in mysql_inplace_alter_table (thd=0x7f5368000d90, table_list=0x7f53680127e8, table=0x7f53680aa5a0, altered_table=0x7f536809e960, ha_alter_info=0x7f53bbfb1030, inplace_supported=HA_ALTER_INPLACE_SHARED_LOCK_AFTER_PREPARE, target_mdl_request=0x7f53bbfb10c0, alter_ctx=0x7f53bbfb1670) at /data/src/10.2/sql/sql_table.cc:7458

#15 0x000055a11d8f77c8 in mysql_alter_table (thd=0x7f5368000d90, new_db=0x7f5368012e00 "test", new_name=0x0, create_info=0x7f53bbfb2290, table_list=0x7f53680127e8, alter_info=0x7f53bbfb21e0, order_num=0, order=0x0, ignore=false) at /data/src/10.2/sql/sql_table.cc:9627

#16 0x000055a11d975e98 in Sql_cmd_alter_table::execute (this=0x7f5368012e08, thd=0x7f5368000d90) at /data/src/10.2/sql/sql_alter.cc:333

#17 0x000055a11d82404d in mysql_execute_command (thd=0x7f5368000d90) at /data/src/10.2/sql/sql_parse.cc:5994

#18 0x000055a11d829065 in mysql_parse (thd=0x7f5368000d90, rawbuf=0x7f53680126f8 "ALTER TABLE t1 ROW_FORMAT=REDUNDANT", length=35, parser_state=0x7f53bbfb35f0, is_com_multi=false, is_next_command=false) at /data/src/10.2/sql/sql_parse.cc:7763

#19 0x000055a11d81733e in dispatch_command (command=COM_QUERY, thd=0x7f5368000d90, packet=0x7f5368008b51 "ALTER TABLE t1 ROW_FORMAT=REDUNDANT", packet_length=35, is_com_multi=false, is_next_command=false) at /data/src/10.2/sql/sql_parse.cc:1827

#20 0x000055a11d815e39 in do_command (thd=0x7f5368000d90) at /data/src/10.2/sql/sql_parse.cc:1381

#21 0x000055a11d97088e in do_handle_one_connection (connect=0x55a1205ad210) at /data/src/10.2/sql/sql_connect.cc:1336

#22 0x000055a11d9705f3 in handle_one_connection (arg=0x55a1205ad210) at /data/src/10.2/sql/sql_connect.cc:1241

#23 0x000055a11e198b82 in pfs_spawn_thread (arg=0x55a120590600) at /data/src/10.2/storage/perfschema/pfs.cc:1869

#24 0x00007f53c60c6609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#25 0x00007f53c5ca2293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95