diff --git a/src/Symfony/Component/Mailer/Transport/Smtp/EsmtpTransport.php b/src/Symfony/Component/Mailer/Transport/Smtp/EsmtpTransport.php
index adfcb55eaa3fb..e3c30487ca6c4 100644
--- a/src/Symfony/Component/Mailer/Transport/Smtp/EsmtpTransport.php
+++ b/src/Symfony/Component/Mailer/Transport/Smtp/EsmtpTransport.php
@@ -173,7 +173,7 @@ private function handleAuth(array $modes): void
                 }
 
                 // keep the error message, but tries the other authenticators
-                $errors[$authenticator->getAuthKeyword()] = $e;
+                $errors[$authenticator->getAuthKeyword()] = $e->getMessage();
             }
         }