@@ -279,7 +279,6 @@
 alter table boundary_255
 modify a varchar(70) charset utf8mb4,
 algorithm=instant;
-ERROR 0A000: ALGORITHM=INSTANT is not supported. Reason: Cannot change column type. Try ALGORITHM=COPY
 drop table boundary_255;
 create table t (
 a char(10) collate utf8mb3_general_ci,
@@ -297,32 +296,21 @@
 repeat('a', 10), repeat('a', 10)
 );
 alter table t modify a char(10) collate utf8mb4_general_ci, algorithm=instant;
-check table t;
-Table	Op	Msg_type	Msg_text
-test.t	check	status	OK
+ERROR 0A000: ALGORITHM=INSTANT is not supported. Reason: Cannot change column type. Try ALGORITHM=COPY
 alter table t modify b char(70) collate utf8mb4_general_ci, algorithm=instant;
-check table t;
-Table	Op	Msg_type	Msg_text
-test.t	check	status	OK
+ERROR 0A000: ALGORITHM=INSTANT is not supported. Reason: Cannot change column type. Try ALGORITHM=COPY
 alter table t modify c char(100) collate utf8mb4_general_ci, algorithm=instant;
-check table t;
-Table	Op	Msg_type	Msg_text
-test.t	check	status	OK
+ERROR 0A000: ALGORITHM=INSTANT is not supported. Reason: Cannot change column type. Try ALGORITHM=COPY
 alter table t modify aa char(10) collate utf8mb4_general_ci, algorithm=instant;
-check table t;
-Table	Op	Msg_type	Msg_text
-test.t	check	status	OK
+ERROR 0A000: ALGORITHM=INSTANT is not supported. Reason: Cannot change column type. Try ALGORITHM=COPY
 alter table t modify bb char(70) collate utf8mb4_general_ci, algorithm=instant;
-check table t;
-Table	Op	Msg_type	Msg_text
-test.t	check	status	OK
+ERROR 0A000: ALGORITHM=INSTANT is not supported. Reason: Cannot change column type. Try ALGORITHM=COPY
 alter table t modify cc char(100) collate utf8mb4_general_ci, algorithm=instant;
-check table t;
-Table	Op	Msg_type	Msg_text
-test.t	check	status	OK
+ERROR 0A000: ALGORITHM=INSTANT is not supported. Reason: Cannot change column type. Try ALGORITHM=COPY
 alter table t modify d char(10) collate utf8mb4_spanish_ci, algorithm=instant;
+ERROR 0A000: ALGORITHM=INSTANT is not supported. Reason: Cannot change column type. Try ALGORITHM=COPY
 alter table t modify dd char(10) collate utf8mb4_spanish_ci, algorithm=instant;
-ERROR 0A000: ALGORITHM=INSTANT is not supported. Reason: ADD INDEX. Try ALGORITHM=NOCOPY
+ERROR 0A000: ALGORITHM=INSTANT is not supported. Reason: Cannot change column type. Try ALGORITHM=COPY
 select * from t;
 a	b	c	aa	bb	cc	d	dd
 aaaaaaaaaa	aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa	aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa	aaaaaaaaaa	aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa	aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa	aaaaaaaaaa	aaaaaaaaaa
@@ -2066,7 +2054,7 @@
 ALTER TABLE t1
 CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci,
 ADD UNIQUE INDEX test_key (a);
-ERROR 23000: Duplicate entry 'NULL' for key 'test_key'
+ERROR 23000: Duplicate entry 'a1' for key 'test_key'
 ALTER TABLE t1 CONVERT TO CHARACTER SET UTF8MB4 COLLATE UTF8MB4_UNICODE_520_CI;
 CHECK TABLE t1;
 Table	Op	Msg_type	Msg_text