diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/CachePoolPass.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/CachePoolPass.php
index db1430eb49b1..eda6f936bf7b 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/CachePoolPass.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/CachePoolPass.php
@@ -11,6 +11,7 @@
 
 namespace Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler;
 
+use Symfony\Component\Cache\Adapter\ArrayAdapter;
 use Symfony\Component\Cache\Adapter\RedisAdapter;
 use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
@@ -70,7 +71,7 @@ public function process(ContainerBuilder $container)
             }
             $i = 0;
             foreach ($attributes as $attr) {
-                if (isset($tags[0][$attr])) {
+                if (isset($tags[0][$attr]) && ('namespace' !== $attr || ArrayAdapter::class !== $adapter->getClass())) {
                     $pool->replaceArgument($i++, $tags[0][$attr]);
                 }
                 unset($tags[0][$attr]);
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Compiler/CachePoolPassTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Compiler/CachePoolPassTest.php
index 6fe6b30eb36c..e9b9bbc778ca 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Compiler/CachePoolPassTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Compiler/CachePoolPassTest.php
@@ -13,6 +13,7 @@
 
 use PHPUnit\Framework\TestCase;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\CachePoolPass;
+use Symfony\Component\Cache\Adapter\ArrayAdapter;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\DefinitionDecorator;
@@ -49,6 +50,24 @@ public function testNamespaceArgumentIsReplaced()
         $this->assertSame('D07rhFx97S', $cachePool->getArgument(0));
     }
 
+    public function testNamespaceArgumentIsNotReplacedIfArrayAdapterIsUsed()
+    {
+        $container = new ContainerBuilder();
+        $container->setParameter('kernel.environment', 'prod');
+        $container->setParameter('kernel.name', 'app');
+        $container->setParameter('kernel.root_dir', 'foo');
+
+        $container->register('cache.adapter.array', ArrayAdapter::class)->addArgument(0);
+
+        $cachePool = new DefinitionDecorator('cache.adapter.array');
+        $cachePool->addTag('cache.pool');
+        $container->setDefinition('app.cache_pool', $cachePool);
+
+        $this->cachePoolPass->process($container);
+
+        $this->assertCount(0, $container->getDefinition('app.cache_pool')->getArguments());
+    }
+
     public function testArgsAreReplaced()
     {
         $container = new ContainerBuilder();