diff --git a/src/Symfony/Component/Notifier/Bridge/Slack/SlackTransport.php b/src/Symfony/Component/Notifier/Bridge/Slack/SlackTransport.php
index ba98e8847d1b..44fc52772261 100644
--- a/src/Symfony/Component/Notifier/Bridge/Slack/SlackTransport.php
+++ b/src/Symfony/Component/Notifier/Bridge/Slack/SlackTransport.php
@@ -95,7 +95,9 @@ protected function doSend(MessageInterface $message): SentMessage
 
         $result = $response->toArray(false);
         if (!$result['ok']) {
-            throw new TransportException(sprintf('Unable to post the Slack message: "%s".', $result['error']), $response);
+            $errors = isset($result['errors']) ? ' ('.implode('|', $result['errors']).')' : '';
+
+            throw new TransportException(sprintf('Unable to post the Slack message: "%s"%s.', $result['error'], $errors), $response);
         }
 
         $sentMessage = new SentMessage($message, (string) $this);
diff --git a/src/Symfony/Component/Notifier/Bridge/Slack/Tests/SlackTransportTest.php b/src/Symfony/Component/Notifier/Bridge/Slack/Tests/SlackTransportTest.php
index c0ebbb6777ec..2b3e96e6b441 100644
--- a/src/Symfony/Component/Notifier/Bridge/Slack/Tests/SlackTransportTest.php
+++ b/src/Symfony/Component/Notifier/Bridge/Slack/Tests/SlackTransportTest.php
@@ -239,4 +239,32 @@ public function testSendIncludesContentTypeWithCharset()
 
         $transport->send(new ChatMessage('testMessage'));
     }
+
+    public function testSendWithErrorsIncluded()
+    {
+        $response = $this->createMock(ResponseInterface::class);
+
+        $response->expects($this->exactly(2))
+            ->method('getStatusCode')
+            ->willReturn(200);
+
+        $response->expects($this->once())
+            ->method('getContent')
+            ->willReturn(json_encode([
+                'ok' => false,
+                'error' => 'invalid_blocks',
+                'errors' => ['no more than 50 items allowed [json-pointer:/blocks]'],
+            ]));
+
+        $client = new MockHttpClient(function () use ($response): ResponseInterface {
+            return $response;
+        });
+
+        $transport = $this->createTransport($client, 'testChannel');
+
+        $this->expectException(TransportException::class);
+        $this->expectExceptionMessage('Unable to post the Slack message: "invalid_blocks" (no more than 50 items allowed [json-pointer:/blocks]).');
+
+        $transport->send(new ChatMessage('testMessage'));
+    }
 }