diff --git a/src/Exceptions/ConnectionWrongData.php b/src/Exceptions/ConnectionWrongData.php
index 6c83598..a745053 100644
--- a/src/Exceptions/ConnectionWrongData.php
+++ b/src/Exceptions/ConnectionWrongData.php
@@ -6,8 +6,8 @@
 
 class ConnectionWrongData extends Exception
 {
-    public function __construct(string $message = '', Throwable $previous = null)
+    public function __construct(string $message = '', $code = 300, Throwable $previous = null)
     {
-        parent::__construct($message, 3, $previous);
+        parent::__construct($message, $code, $previous);
     }
 }
diff --git a/src/Exceptions/RelationWrongData.php b/src/Exceptions/RelationWrongData.php
index ca7de04..0bd37a3 100644
--- a/src/Exceptions/RelationWrongData.php
+++ b/src/Exceptions/RelationWrongData.php
@@ -2,6 +2,12 @@
 
 namespace iTRON\wpConnections\Exceptions;
 
+use Throwable;
+
 class RelationWrongData extends Exception
 {
+    public function __construct(string $message = '', $code = 400, Throwable $previous = null)
+    {
+        parent::__construct($message, $code, $previous);
+    }
 }
diff --git a/src/Relation.php b/src/Relation.php
index c039fac..0e2c59b 100644
--- a/src/Relation.php
+++ b/src/Relation.php
@@ -42,7 +42,7 @@ public function createConnection(Query\Connection $connectionQuery): Connection
 
         // Self-connection ability
         if (! $this->closurable && $connectionQuery->get('from') === $connectionQuery->get('to')) {
-            throw new Exceptions\ConnectionWrongData('Closurable not allowed by relation settings.');
+            throw new Exceptions\ConnectionWrongData('Closurable not allowed by relation settings.', 301);
         }
 
         // Cardinality check
@@ -56,7 +56,7 @@ public function createConnection(Query\Connection $connectionQuery): Connection
 
             $check_output = $this->findConnections($query);
             if (! $check_output->isEmpty()) {
-                throw new Exceptions\ConnectionWrongData('Cardinality violation.');
+                throw new Exceptions\ConnectionWrongData('Cardinality violation.', 302);
             }
         }
 
@@ -66,7 +66,7 @@ public function createConnection(Query\Connection $connectionQuery): Connection
 
             $check_input = $this->findConnections($query);
             if (! $check_input->isEmpty()) {
-                throw new Exceptions\ConnectionWrongData('Cardinality violation.');
+                throw new Exceptions\ConnectionWrongData('Cardinality violation.', 302);
             }
         }
 
@@ -77,7 +77,7 @@ public function createConnection(Query\Connection $connectionQuery): Connection
         if (! $this->duplicatable) {
             $check_duplicatable = $this->findConnections($query);
             if (!$check_duplicatable->isEmpty()) {
-                throw new Exceptions\ConnectionWrongData('Duplicatable violation.');
+                throw new Exceptions\ConnectionWrongData('Duplicatable violation.', 303);
             }
         }