diff --git a/src/Symfony/Component/Cache/DoctrineProvider.php b/src/Symfony/Component/Cache/DoctrineProvider.php
index cebe95fbc7..4c5cd0cb1f 100644
--- a/src/Symfony/Component/Cache/DoctrineProvider.php
+++ b/src/Symfony/Component/Cache/DoctrineProvider.php
@@ -90,7 +90,7 @@ class DoctrineProvider extends CacheProvider implements PruneableInterface, Rese
      */
     protected function doFlush()
     {
-        $this->pool->clear();
+        return $this->pool->clear();
     }
 
     /**
@@ -98,5 +98,6 @@ class DoctrineProvider extends CacheProvider implements PruneableInterface, Rese
      */
     protected function doGetStats()
     {
+        return null;
     }
 }
diff --git a/src/Symfony/Component/Cache/Tests/Adapter/MaxIdLengthAdapterTest.php b/src/Symfony/Component/Cache/Tests/Adapter/MaxIdLengthAdapterTest.php
index a803988d05..909191960f 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/MaxIdLengthAdapterTest.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/MaxIdLengthAdapterTest.php
@@ -40,6 +40,10 @@ class MaxIdLengthAdapterTest extends TestCase
             ->setConstructorArgs([str_repeat('-', 26)])
             ->getMock();
 
+        $cache
+            ->method('doFetch')
+            ->willReturn(['2:']);
+
         $reflectionClass = new \ReflectionClass(AbstractAdapter::class);
 
         $reflectionMethod = $reflectionClass->getMethod('getId');
@@ -56,7 +60,7 @@ class MaxIdLengthAdapterTest extends TestCase
         $reflectionProperty->setValue($cache, true);
 
         // Versioning enabled
-        $this->assertEquals('--------------------------:1:------------', $reflectionMethod->invokeArgs($cache, [str_repeat('-', 12)]));
+        $this->assertEquals('--------------------------:2:------------', $reflectionMethod->invokeArgs($cache, [str_repeat('-', 12)]));
         $this->assertLessThanOrEqual(50, \strlen($reflectionMethod->invokeArgs($cache, [str_repeat('-', 12)])));
         $this->assertLessThanOrEqual(50, \strlen($reflectionMethod->invokeArgs($cache, [str_repeat('-', 23)])));
         $this->assertLessThanOrEqual(50, \strlen($reflectionMethod->invokeArgs($cache, [str_repeat('-', 40)])));