diff --git a/src/Symfony/Component/HttpClient/Response/AmpResponseV5.php b/src/Symfony/Component/HttpClient/Response/AmpResponseV5.php
index 8f56c76a41033..7fc1036d4c34e 100644
--- a/src/Symfony/Component/HttpClient/Response/AmpResponseV5.php
+++ b/src/Symfony/Component/HttpClient/Response/AmpResponseV5.php
@@ -240,6 +240,10 @@ private static function generateResponse(Request $request, AmpClientStateV5 $mul
             $body = $response->getBody();
 
             while (true) {
+                if (!isset($multi->openHandles[$id])) {
+                    return;
+                }
+
                 $multi->openHandles[$id]->complete();
                 $multi->openHandles[$id] = new DeferredFuture();