diff --git a/mysql-test/suite/innodb/r/innodb_bug12661768.result b/mysql-test/suite/innodb/r/innodb_bug12661768.result
new file mode 100644
index 00000000000..1f2401ddd47
--- /dev/null
+++ b/mysql-test/suite/innodb/r/innodb_bug12661768.result
@@ -0,0 +1,2 @@
+SET SESSION foreign_key_checks=0;
+ERROR 23000: Upholding foreign key constraints for table 'bug12661768_1', entry '3-bbb', key 2 would lead to a duplicate entry
diff --git a/mysql-test/suite/innodb/t/innodb_bug12661768.test b/mysql-test/suite/innodb/t/innodb_bug12661768.test
new file mode 100644
index 00000000000..01549a7e9e9
--- /dev/null
+++ b/mysql-test/suite/innodb/t/innodb_bug12661768.test
@@ -0,0 +1,50 @@
+#
+# Bug#12661768 UPDATE IGNORE CRASHES SERVER IF TABLE IS INNODB AND IT IS
+# PARENT FOR OTHER ONE
+#
+
+-- source include/have_innodb.inc
+
+SET SESSION foreign_key_checks=0;
+
+# only interested that the "UPDATE IGNORE" at the end does not crash the server
+
+-- disable_query_log
+-- disable_result_log
+
+SET NAMES utf8;
+
+-- let $t1_name = bug12661768_1
+-- let $t2_name = bug12661768_2
+-- let $fk_name = ab_on_2
+-- let $key_str = 'bbb'
+
+eval DROP TABLE IF EXISTS `$t2_name`, `$t1_name`;
+
+eval CREATE TABLE `$t1_name` (
+	a INT,
+	b VARCHAR(512),
+	PRIMARY KEY (a, b)
+) ENGINE=INNODB;
+
+eval CREATE TABLE `$t2_name` (
+	id INT,
+	a INT,
+	b VARCHAR(512),
+	PRIMARY KEY (id),
+	UNIQUE KEY `$fk_name` (a, b),
+	FOREIGN KEY (a, b) REFERENCES `$t1_name` (a, b)
+	ON DELETE CASCADE ON UPDATE CASCADE
+) ENGINE=INNODB;
+
+eval INSERT INTO `$t1_name` VALUES (1, $key_str);
+eval INSERT INTO `$t2_name` VALUES (100, 1, $key_str), (101, 3, $key_str);
+
+SET SESSION foreign_key_checks=1;
+
+-- enable_result_log
+
+-- error ER_FOREIGN_DUPLICATE_KEY
+eval UPDATE IGNORE `$t1_name` SET a = 3;
+
+eval DROP TABLE `$t2_name`, `$t1_name`;
diff --git a/sql/handler.cc b/sql/handler.cc
index 82f5f2ee841..895e7cc4df0 100644
--- a/sql/handler.cc
+++ b/sql/handler.cc
@@ -2692,7 +2692,13 @@ void handler::print_error(int error, myf errflag)
       char key[MAX_KEY_LENGTH];
       String str(key,sizeof(key),system_charset_info);
       /* Table is opened and defined at this point */
-      key_unpack(&str,table,(uint) key_nr);
+      key_unpack(&str,table,0 /* Use 0 instead of key_nr because key_nr
+                 is a key number in the child FK table, not in our 'table'. See
+		 Bug#12661768 UPDATE IGNORE CRASHES SERVER IF TABLE IS INNODB
+		 AND IT IS PARENT FOR OTHER ONE
+		 This bug gets a better fix in MySQL 5.6, but it is too risky
+		 to get that in 5.1 and 5.5 (extending the handler interface
+		 and adding new error message codes */);
       max_length= (MYSQL_ERRMSG_SIZE-
                    (uint) strlen(ER(ER_FOREIGN_DUPLICATE_KEY)));
       if (str.length() >= max_length)