Also putting charset option in a place where it is committed

doctrine/doctrine-bundle/1.6/config/packages/doctrine.yaml

@@ -10,6 +10,7 @@ doctrine:
         # configure these for your database server
         driver: 'pdo_mysql'
         server_version: '5.7'
+        charset: utf8mb4
 
         # With Symfony 3.3, remove the `resolve:` prefix
         url: '%env(resolve:DATABASE_URL)%'

doctrine/doctrine-bundle/1.6/manifest.json

@@ -10,6 +10,6 @@
         "#1": "Format described at http://docs.doctrine-project.org/projects/doctrine-dbal/en/latest/reference/configuration.html#connecting-using-a-url",
         "#2": "For an SQLite database, use: \"sqlite:///%kernel.project_dir%/var/data.db\"",
         "#3": "Set \"serverVersion\" to your server version to avoid edge-case exceptions and extra database calls",
-        "DATABASE_URL": "mysql://db_user:db_password@127.0.0.1:3306/db_name?charset=utf8mb4"
+        "DATABASE_URL": "mysql://db_user:db_password@127.0.0.1:3306/db_name"
     }
 }