diff --git a/mysql-test/suite/innodb/r/innodb-alter-debug.result b/mysql-test/suite/innodb/r/innodb-alter-debug.result
index 78976030ac8..d888fb5b034 100644
--- a/mysql-test/suite/innodb/r/innodb-alter-debug.result
+++ b/mysql-test/suite/innodb/r/innodb-alter-debug.result
@@ -54,3 +54,17 @@ SET DEBUG_SYNC = 'now SIGNAL s2';
 ERROR 23000: Duplicate entry '1' for key 'uk'
 SET DEBUG_SYNC = 'RESET';
 drop table t1;
+#
+# Bug #27753193  ASSERTION `PREBUILT->TRX->ERROR_KEY_NUM <
+#                HA_ALTER_INFO->KEY_COUNT'
+CREATE TABLE t1 (a INT, UNIQUE KEY(a)) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1);
+SET DEBUG_SYNC = 'row_log_table_apply1_before signal S1 WAIT_FOR S2';
+ALTER TABLE t1 FORCE, ALGORITHM=INPLACE;
+SET DEBUG_SYNC = 'now WAIT_FOR S1';
+INSERT INTO t1 VALUES (1);
+ERROR 23000: Duplicate entry '1' for key 'a'
+SET DEBUG_SYNC = 'now SIGNAL S2';
+ERROR 23000: Duplicate entry '1' for key 'a'
+SET DEBUG_SYNC='RESET';
+DROP TABLE t1;
diff --git a/mysql-test/suite/innodb/t/innodb-alter-debug.test b/mysql-test/suite/innodb/t/innodb-alter-debug.test
index f4996916e9f..bc4b2ad8e56 100644
--- a/mysql-test/suite/innodb/t/innodb-alter-debug.test
+++ b/mysql-test/suite/innodb/t/innodb-alter-debug.test
@@ -64,7 +64,6 @@ set DEBUG_SYNC = 'now WAIT_FOR s1';
 --error ER_DUP_ENTRY
 update t1 set a=1 where id=2;
 SET DEBUG_SYNC = 'now SIGNAL s2';
-disconnect con1;
 
 --echo /* connection default */
 connection default;
@@ -75,5 +74,29 @@ SET DEBUG_SYNC = 'RESET';
 
 drop table t1;
 
+--echo #
+--echo # Bug #27753193  ASSERTION `PREBUILT->TRX->ERROR_KEY_NUM <
+--echo #                HA_ALTER_INFO->KEY_COUNT'
+
+CREATE TABLE t1 (a INT, UNIQUE KEY(a)) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1);
+
+SET DEBUG_SYNC = 'row_log_table_apply1_before signal S1 WAIT_FOR S2';
+send ALTER TABLE t1 FORCE, ALGORITHM=INPLACE;
+
+connection con1;
+SET DEBUG_SYNC = 'now WAIT_FOR S1';
+--error ER_DUP_ENTRY
+INSERT INTO t1 VALUES (1);
+SET DEBUG_SYNC = 'now SIGNAL S2';
+disconnect con1;
+
+CONNECTION default;
+--error ER_DUP_ENTRY
+reap;
+SET DEBUG_SYNC='RESET';
+
+DROP TABLE t1;
+
 # Wait till all disconnects are completed
 --source include/wait_until_count_sessions.inc
diff --git a/storage/innobase/include/univ.i b/storage/innobase/include/univ.i
index 8cd3f85f835..a9d886607c0 100644
--- a/storage/innobase/include/univ.i
+++ b/storage/innobase/include/univ.i
@@ -45,7 +45,7 @@ Created 1/20/1994 Heikki Tuuri
 
 #define INNODB_VERSION_MAJOR	5
 #define INNODB_VERSION_MINOR	6
-#define INNODB_VERSION_BUGFIX	41
+#define INNODB_VERSION_BUGFIX	42
 
 /* The following is the InnoDB version as shown in
 SELECT plugin_version FROM information_schema.plugins;