diff --git a/tests/e2e/Controllers/PlanControllerTest.php b/tests/e2e/Controllers/PlanControllerTest.php
index 5d99621..913583a 100644
--- a/tests/e2e/Controllers/PlanControllerTest.php
+++ b/tests/e2e/Controllers/PlanControllerTest.php
@@ -199,4 +199,23 @@ class PlanControllerTest extends TestCase
         $body = json_decode($response->getBody(), true);
         $this->assertArrayHasKey('error', $body);
     }
+
+    public function test_create_plan_returns_404_when_user_not_found(): void
+    {
+        $response = $this->controller->createPlan(
+            $this->makeRequest([
+                'userId' => 99,
+                'textId' => 0,
+                'name' => 'My Plan',
+                'dateStart' => '2025-01-01',
+                'dateEnd' => '2025-01-01',
+            ]),
+            new Response(),
+            $this->createPlan,
+        );
+
+        $this->assertEquals(404, $response->getStatusCode());
+        $body = json_decode($response->getBody(), true);
+        $this->assertArrayHasKey('error', $body);
+    }
 }