Symfony 6.4.9 has just been released.
Here is the list of the most important changes since 6.4.8:

• bug #57553 [HttpKernel] Enable optional cache-warmers when cache-dir != build-dir (@nicolas-grekas)
• bug #57497 [String] Fixed u()->snake(), b()->snake() and s()->snake() methods (@arczinosek)
• bug #57574 [Filesystem] Fix Filesystem::remove() on Windows (@nicolas-grekas)
• bug #57572 [DoctrineBridge] Fix compat with DI >= 6.4 (@nicolas-grekas)
• bug #57538 [String] Add alias case to EnglishInflector (@alexandre-daubois)
• bug #57533 [FrameworkBundle] Throw runtime exception when trying to use asset-mapper while http-client is disabled (@nicolas-grekas)
• bug #57520 [SecurityBundle] Remove unused memory users’ name attribute from the XSD (@MatTheCat)
• feature #57557 Ibexa is sponsoring Symfony 5.4, thanks to them! \o/ (@nicolas-grekas)
• bug #57569 [HttpClient][Mailer] Revert "Let curl handle transfer encoding", use HTTP/1.1 for Mailgun (@nicolas-grekas)
• bug #57499 [Mailer] Add additional headers in Scaleway bridge (@MrMicky-FR)
• bug #57460 [VarExporter] fix contravariance problem with __unserialize() in lazy proxy (@nikophil)
• bug #57397 [VarDumper] Fix FFI caster test (@alexandre-daubois)
• bug #57453 [HttpClient] Fix parsing SSE (@fancyweb)
• bug #57467 [SecurityBundle] Add provider XML attribute to the authenticators it’s missing from (@MatTheCat)
• bug #57384 [Notifier] Fix thread key in GoogleChat bridge (@romain-jacquart)
• bug #57372 [HttpKernel][Security] Fix accessing session for stateless request (@VincentLanglet)
• bug #57112 [Messenger] Handle AMQPConnectionException when publishing a message (@jwage)
• bug #57341 [Serializer] properly handle invalid data for false/true types (@xabbuh)
• bug #57187 [Serializer] Fix ObjectNormalizer with property path (@HypeMC)
• bug #57355 [ErrorHandler] Fix rendered exception code highlighting on PHP 8.3 (@tscni)
• bug #57310 [DependencyInjection] Fix ternary in AutowireCallable attribute (@alamirault)
• bug #57273 [FrameworkBundle] Fix setting default context for certain normalizers (@HypeMC)
• bug #57395 [Notifier] send the recipient phone number as an array (@xabbuh)
• bug #52699 [Serializer] [PropertyAccessor] Ignore non-collection interface generics (@mtarld)
• bug #54634 [String] Fix #54611 pluralization of -on ending words + singularization of -a ending foreign words (@Geordie, @DesLynx)
• bug #57213 [Validator] [UniqueValidator] Use correct variable as parameter in (custom) error message (@seho-nl, Sebastien Hoek)
• bug #54920 [Messenger] Comply with Amazon SQS requirements for message body (@VincentLanglet)
• bug #57321 [AssetMapper] fix npm version constraint conversion (@Jean-Beru)
• bug #57110 [PhpUnitBridge] Fix error handler triggered outside of tests (@HypeMC)
• bug #57297 [FrameworkBundle] not registered definitions must not be modified (@xabbuh)
• bug #57234 [String] Fix Inflector for 'hardware' (@podhy)
• bug #57224 [Mime] Use streams instead of loading raw message generator into memory (@bytestream)

Want to upgrade to this new release? Because Symfony protects
backwards-compatibility very closely, this should be quite easy. Use
SymfonyInsight upgrade reports
to detect the code you will need to change in your project and
read our upgrade
documentation to learn more.
Want to be notified whenever a new Symfony release is published? Or when a
version is not maintained anymore? Or only when a security issue is fixed?
Consider subscribing to the Symfony Roadmap Notifications.

Sponsor the Symfony project.