diff --git a/src/Symfony/Component/HttpClient/Response/MockResponse.php b/src/Symfony/Component/HttpClient/Response/MockResponse.php
index dc65a49fa96c6..b8954e6732cd3 100644
--- a/src/Symfony/Component/HttpClient/Response/MockResponse.php
+++ b/src/Symfony/Component/HttpClient/Response/MockResponse.php
@@ -90,17 +90,11 @@ public function getRequestMethod(): string
         return $this->requestMethod;
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function getInfo(?string $type = null)
     {
         return null !== $type ? $this->info[$type] ?? null : $this->info;
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function cancel(): void
     {
         $this->info['canceled'] = true;
@@ -116,9 +110,6 @@ public function cancel(): void
         $onProgress($this->offset, $dlSize, $this->info);
     }
 
-    /**
-     * {@inheritdoc}
-     */
     protected function close(): void
     {
         $this->inflate = null;
@@ -159,9 +150,6 @@ public static function fromRequest(string $method, string $url, array $options,
         return $response;
     }
 
-    /**
-     * {@inheritdoc}
-     */
     protected static function schedule(self $response, array &$runningResponses): void
     {
         if (!$response->id) {
@@ -177,9 +165,6 @@ protected static function schedule(self $response, array &$runningResponses): vo
         $runningResponses[0][1][$response->id] = $response;
     }
 
-    /**
-     * {@inheritdoc}
-     */
     protected static function perform(ClientState $multi, array &$responses): void
     {
         foreach ($responses as $response) {
@@ -203,7 +188,7 @@ protected static function perform(ClientState $multi, array &$responses): void
                     $chunk[1]->getStatusCode();
                     $chunk[1]->getHeaders(false);
                     self::readResponse($response, $chunk[0], $chunk[1], $offset);
-                    $multi->handlesActivity[$id][] = new FirstChunk();
+                    $multi->handlesActivity[$id][] = ($response->body[0] ?? null) instanceof ErrorChunk ? $response->body[0] : new FirstChunk();
                     $buffer = $response->requestOptions['buffer'] ?? null;
 
                     if ($buffer instanceof \Closure && $response->content = $buffer($response->headers) ?: null) {
@@ -223,9 +208,6 @@ protected static function perform(ClientState $multi, array &$responses): void
         }
     }
 
-    /**
-     * {@inheritdoc}
-     */
     protected static function select(ClientState $multi, float $timeout): int
     {
         return 42;
diff --git a/src/Symfony/Component/HttpClient/Tests/Response/MockResponseTest.php b/src/Symfony/Component/HttpClient/Tests/Response/MockResponseTest.php
index 0afac4ec74722..75792e2882fd4 100644
--- a/src/Symfony/Component/HttpClient/Tests/Response/MockResponseTest.php
+++ b/src/Symfony/Component/HttpClient/Tests/Response/MockResponseTest.php
@@ -13,6 +13,7 @@
 
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\HttpClient\Exception\JsonException;
+use Symfony\Component\HttpClient\Exception\TimeoutException;
 use Symfony\Component\HttpClient\Exception\TransportException;
 use Symfony\Component\HttpClient\Response\MockResponse;
 
@@ -124,4 +125,34 @@ public function testCancelingAMockResponseNotIssuedByMockHttpClient()
 
         $this->assertTrue($mockResponse->getInfo('canceled'));
     }
+
+    public function testTimeoutHeader()
+    {
+        $response = MockResponse::fromRequest('GET', 'http://symfony.com', [], new MockResponse(['']));
+
+        try {
+            $response->getStatusCode();
+            $this->fail(TimeoutException::class.' expected');
+        } catch (TimeoutException $e) {
+        }
+
+        $this->assertSame('Idle timeout reached for "http://symfony.com".', $response->getInfo('error'));
+    }
+
+    public function testTimeoutBody()
+    {
+        $response = MockResponse::fromRequest('GET', 'http://symfony.com', [], new MockResponse(['content', '']));
+
+        try {
+            $this->assertSame(200, $response->getStatusCode());
+        } catch (TimeoutException $e) {
+            $this->fail(TimeoutException::class.' was not expected');
+        }
+
+        try {
+            $response->getContent();
+            $this->fail(TimeoutException::class.' expected');
+        } catch (TimeoutException $e) {
+        }
+    }
 }