diff --git a/framework/UPGRADE.md b/framework/UPGRADE.md
index 9f39e5ad8a..ebb0902190 100644
--- a/framework/UPGRADE.md
+++ b/framework/UPGRADE.md
@@ -117,7 +117,7 @@ new ones save the following code as `convert.php` that should be placed in the s
       foreach ($oldData['items'] as $name => $data) {
           if (isset($data['assignments'])) {
               foreach ($data['assignments'] as $userId => $assignmentData) {
-                  $assignments[$userId] = $assignmentData['roleName'];
+                  $assignments[$userId][] = $assignmentData['roleName'];
               }
               unset($data['assignments']);
           }
diff --git a/framework/rbac/PhpManager.php b/framework/rbac/PhpManager.php
index 08a6e90a6b..3dd1a77bba 100644
--- a/framework/rbac/PhpManager.php
+++ b/framework/rbac/PhpManager.php
@@ -644,12 +644,14 @@ class PhpManager extends BaseManager
             }
         }
 
-        foreach ($assignments as $userId => $role) {
-            $this->assignments[$userId][$role] = new Assignment([
-                'userId' => $userId,
-                'roleName' => $role,
-                'createdAt' => $assignmentsMtime,
-            ]);
+        foreach ($assignments as $userId => $roles) {
+            foreach ($roles as $role) {
+                $this->assignments[$userId][$role] = new Assignment([
+                    'userId' => $userId,
+                    'roleName' => $role,
+                    'createdAt' => $assignmentsMtime,
+                ]);
+            }
         }
 
         foreach ($rules as $name => $ruleData) {
@@ -730,7 +732,7 @@ class PhpManager extends BaseManager
         foreach ($this->assignments as $userId => $assignments) {
             foreach ($assignments as $name => $assignment) {
                 /* @var $assignment Assignment */
-                $assignmentData[$userId] = $assignment->roleName;
+                $assignmentData[$userId][] = $assignment->roleName;
             }
         }
         $this->saveToFile($assignmentData, $this->assignmentFile);
diff --git a/tests/unit/framework/rbac/DbManagerTestCase.php b/tests/unit/framework/rbac/DbManagerTestCase.php
index f8795d7f86..043b86ad11 100644
--- a/tests/unit/framework/rbac/DbManagerTestCase.php
+++ b/tests/unit/framework/rbac/DbManagerTestCase.php
@@ -70,8 +70,7 @@ abstract class DbManagerTestCase extends ManagerTestCase
     protected function setUp()
     {
         parent::setUp();
-        $this->auth = new DbManager(['db' => $this->getConnection()]);
-
+        $this->auth = $this->createManager();
     }
 
     protected function tearDown()
@@ -105,4 +104,12 @@ abstract class DbManagerTestCase extends ManagerTestCase
         }
         return static::$db;
     }
+
+    /**
+     * @return \yii\rbac\ManagerInterface
+     */
+    protected function createManager()
+    {
+        return new DbManager(['db' => $this->getConnection()]);
+    }
 }
diff --git a/tests/unit/framework/rbac/ManagerTestCase.php b/tests/unit/framework/rbac/ManagerTestCase.php
index ec12f78646..21a49d44ee 100644
--- a/tests/unit/framework/rbac/ManagerTestCase.php
+++ b/tests/unit/framework/rbac/ManagerTestCase.php
@@ -17,6 +17,11 @@ abstract class ManagerTestCase extends TestCase
      */
     protected $auth;
 
+    /**
+     * @return \yii\rbac\ManagerInterface
+     */
+    abstract protected function createManager();
+
     public function testCreateRole()
     {
         $role = $this->auth->createRole('admin');
@@ -241,6 +246,26 @@ abstract class ManagerTestCase extends TestCase
         $roles = $this->auth->getRolesByUser('reader A');
         $this->assertTrue(reset($roles) instanceof Role);
         $this->assertEquals($roles['reader']->name, 'reader');
+    }
 
+    public function testAssignMultipleRoles()
+    {
+        $this->prepareData();
+
+        $reader = $this->auth->getRole('reader');
+        $author = $this->auth->getRole('author');
+        $this->auth->assign($reader, 'readingAuthor');
+        $this->auth->assign($author, 'readingAuthor');
+
+        $this->auth = $this->createManager();
+
+        $roles = $this->auth->getRolesByUser('readingAuthor');
+        $roleNames = [];
+        foreach ($roles as $role) {
+            $roleNames[] = $role->name;
+        }
+
+        $this->assertContains('reader', $roleNames, 'Roles should contain reader. Currently it has: ' . implode(', ', $roleNames));
+        $this->assertContains('author', $roleNames, 'Roles should contain author. Currently it has: ' . implode(', ', $roleNames));
     }
 }
diff --git a/tests/unit/framework/rbac/PhpManagerTest.php b/tests/unit/framework/rbac/PhpManagerTest.php
index d420b7a51d..8c9c2b9554 100644
--- a/tests/unit/framework/rbac/PhpManagerTest.php
+++ b/tests/unit/framework/rbac/PhpManagerTest.php
@@ -32,6 +32,9 @@ class PhpManagerTest extends ManagerTestCase
         @unlink($this->getRuleFile());
     }
 
+    /**
+     * @inheritdoc
+     */
     protected function createManager()
     {
         return new ExposedPhpManager([