diff --git a/mysql-test/suite/innodb/r/add_constraint.result b/mysql-test/suite/innodb/r/add_constraint.result
new file mode 100644
index 00000000000..cbbcb4e8fa8
--- /dev/null
+++ b/mysql-test/suite/innodb/r/add_constraint.result
@@ -0,0 +1,13 @@
+#
+# Bug #20762798 FK DDL: CRASH IN DICT_FOREIGN_REMOVE_FROM_CACHE
+#
+create table t1(a int, b int, key(a),key(b))engine=innodb;
+create table t2(a int, b int, key(a),key(b))engine=innodb;
+alter table t2 add constraint b foreign key (b) references t1(a);
+alter table t1 add constraint b1 foreign key (b) references t2(a);
+alter table t2 add constraint b1 foreign key (b) references t1(a);
+ERROR HY000: Can't create table '#sql-temporary' (errno: 121)
+alter table t2 drop foreign key b;
+alter table t1 drop foreign key b1;
+drop table t2;
+drop table t1;
diff --git a/mysql-test/suite/innodb/t/add_constraint.test b/mysql-test/suite/innodb/t/add_constraint.test
new file mode 100644
index 00000000000..eabf06434f4
--- /dev/null
+++ b/mysql-test/suite/innodb/t/add_constraint.test
@@ -0,0 +1,21 @@
+--source include/have_innodb.inc
+
+--echo #
+--echo # Bug #20762798 FK DDL: CRASH IN DICT_FOREIGN_REMOVE_FROM_CACHE
+--echo #
+
+create table t1(a int, b int, key(a),key(b))engine=innodb;
+create table t2(a int, b int, key(a),key(b))engine=innodb;
+
+alter table t2 add constraint b foreign key (b) references t1(a);
+alter table t1 add constraint b1 foreign key (b) references t2(a);
+
+--replace_regex /'[^']*test\.#sql-[0-9a-f_]*'/'#sql-temporary'/
+--error ER_CANT_CREATE_TABLE
+alter table t2 add constraint b1 foreign key (b) references t1(a);
+
+alter table t2 drop foreign key b;
+alter table t1 drop foreign key b1;
+
+drop table t2;
+drop table t1;
diff --git a/storage/innobase/dict/dict0dict.c b/storage/innobase/dict/dict0dict.c
index 56baceb7a4b..5aca95aec0d 100644
--- a/storage/innobase/dict/dict0dict.c
+++ b/storage/innobase/dict/dict0dict.c
@@ -2533,10 +2533,14 @@ dict_foreign_remove_from_cache(
 		if (rbt != NULL && foreign->id != NULL) {
 			const ib_rbt_node_t*	node
 				= rbt_lookup(rbt, foreign->id);
-			dict_foreign_t*	val = *(dict_foreign_t**) node->value;
 
-			if (val == foreign) {
-				rbt_delete(rbt, foreign->id);
+			if (node != NULL) {
+				dict_foreign_t*	val
+					= *(dict_foreign_t**) node->value;
+
+				if (val == foreign) {
+					rbt_delete(rbt, foreign->id);
+				}
 			}
 		}
 	}
@@ -2552,10 +2556,14 @@ dict_foreign_remove_from_cache(
 		if (rbt != NULL && foreign->id != NULL) {
 			const ib_rbt_node_t*	node
 				= rbt_lookup(rbt, foreign->id);
-			dict_foreign_t*	val = *(dict_foreign_t**) node->value;
 
-			if (val == foreign) {
-				rbt_delete(rbt, foreign->id);
+			if (node != NULL) {
+				dict_foreign_t*	val
+					= *(dict_foreign_t**) node->value;
+
+				if (val == foreign) {
+					rbt_delete(rbt, foreign->id);
+				}
 			}
 		}
 	}