diff --git a/api/modules/authserver/exceptions/IllegalArgumentException.php b/api/modules/authserver/exceptions/IllegalArgumentException.php
index 11adfa6..898daee 100644
--- a/api/modules/authserver/exceptions/IllegalArgumentException.php
+++ b/api/modules/authserver/exceptions/IllegalArgumentException.php
@@ -3,8 +3,8 @@ namespace api\modules\authserver\exceptions;
 
 class IllegalArgumentException extends AuthserverException {
 
-    public function __construct($status = null, $message = null, $code = 0, \Exception $previous = null) {
-        parent::__construct(400, 'credentials can not be null.', $code, $previous);
+    public function __construct($message = 'credentials can not be null.') {
+        parent::__construct(400, $message);
     }
 
 }
diff --git a/api/modules/authserver/models/AuthenticationForm.php b/api/modules/authserver/models/AuthenticationForm.php
index aab29bd..b8c8921 100644
--- a/api/modules/authserver/models/AuthenticationForm.php
+++ b/api/modules/authserver/models/AuthenticationForm.php
@@ -5,6 +5,7 @@ use api\models\authentication\LoginForm;
 use api\models\base\ApiForm;
 use api\modules\authserver\exceptions\ForbiddenOperationException;
 use api\modules\authserver\Module as Authserver;
+use api\modules\authserver\validators\ClientTokenValidator;
 use api\modules\authserver\validators\RequiredValidator;
 use common\helpers\Error as E;
 use common\models\Account;
@@ -19,6 +20,7 @@ class AuthenticationForm extends ApiForm {
     public function rules() {
         return [
             [['username', 'password', 'clientToken'], RequiredValidator::class],
+            [['clientToken'], ClientTokenValidator::class],
         ];
     }
 
diff --git a/api/modules/authserver/validators/ClientTokenValidator.php b/api/modules/authserver/validators/ClientTokenValidator.php
new file mode 100644
index 0000000..8825b8f
--- /dev/null
+++ b/api/modules/authserver/validators/ClientTokenValidator.php
@@ -0,0 +1,25 @@
+<?php
+namespace api\modules\authserver\validators;
+
+use api\modules\authserver\exceptions\IllegalArgumentException;
+
+/**
+ * Максимальная длина clientToken для нашей базы данных составляет 255.
+ * После этого мы не принимаем указанный токен
+ */
+class ClientTokenValidator extends \yii\validators\RequiredValidator {
+
+    /**
+     * @param string $value
+     * @return null
+     * @throws \api\modules\authserver\exceptions\AuthserverException
+     */
+    protected function validateValue($value) {
+        if (mb_strlen($value) > 255) {
+            throw new IllegalArgumentException('clientToken is too long.');
+        }
+
+        return null;
+    }
+
+}
diff --git a/console/migrations/m180102_164624_increase_minecraft_access_keys_client_token_length.php b/console/migrations/m180102_164624_increase_minecraft_access_keys_client_token_length.php
new file mode 100644
index 0000000..56c3fbd
--- /dev/null
+++ b/console/migrations/m180102_164624_increase_minecraft_access_keys_client_token_length.php
@@ -0,0 +1,15 @@
+<?php
+
+use console\db\Migration;
+
+class m180102_164624_increase_minecraft_access_keys_client_token_length extends Migration {
+
+    public function safeUp() {
+        $this->alterColumn('{{%minecraft_access_keys}}', 'client_token', $this->string()->notNull());
+    }
+
+    public function safeDown() {
+        $this->alterColumn('{{%minecraft_access_keys}}', 'client_token', $this->string(36)->notNull());
+    }
+
+}
diff --git a/tests/codeception/api/functional/authserver/AuthorizationCest.php b/tests/codeception/api/functional/authserver/AuthorizationCest.php
index 626adb6..2b17c1e 100644
--- a/tests/codeception/api/functional/authserver/AuthorizationCest.php
+++ b/tests/codeception/api/functional/authserver/AuthorizationCest.php
@@ -75,6 +75,31 @@ class AuthorizationCest {
         $this->testSuccessResponse($I);
     }
 
+    public function longClientToken(FunctionalTester $I) {
+        $I->wantTo('send non uuid clientToken, but less then 255 characters');
+        $this->route->authenticate([
+            'username' => 'admin@ely.by',
+            'password' => 'password_0',
+            'clientToken' => str_pad('', 255, 'x'),
+        ]);
+        $this->testSuccessResponse($I);
+    }
+
+    public function tooLongClientToken(FunctionalTester $I) {
+        $I->wantTo('send non uuid clientToken with more then 255 characters length');
+        $this->route->authenticate([
+            'username' => 'admin@ely.by',
+            'password' => 'password_0',
+            'clientToken' => str_pad('', 256, 'x'),
+        ]);
+        $I->canSeeResponseCodeIs(400);
+        $I->canSeeResponseIsJson();
+        $I->canSeeResponseContainsJson([
+            'error' => 'IllegalArgumentException',
+            'errorMessage' => 'clientToken is too long.',
+        ]);
+    }
+
     public function wrongArguments(FunctionalTester $I) {
         $I->wantTo('get error on wrong amount of arguments');
         $this->route->authenticate([