symfony/UPGRADE-4.0.md

UPGRADE FROM 3.x to 4.0

DependencyInjection

• Using unsupported configuration keys in YAML configuration files raises an exception.

• Using unsupported options to configure service aliases raises an exception.

Form

• The choices_as_values option of the ChoiceType has been removed.

Serializer

• The ability to pass a Doctrine Cache instance to the ClassMetadataFactory class has been removed. You should use the CacheClassMetadataFactory class instead.

Yaml

• The !!php/object tag to indicate dumped PHP objects was removed in favor of the !php/object tag.