Symfony 4.4.40 has just been released.
Here is the list of the most important changes since 4.4.39:

bug #45910 [Messenger] reset connection on worker shutdown (@SanderHagen)
bug #45909 [Form][TwigBundle] reset Twig form theme resources between requests (@xabbuh)
bug #45906 [HttpClient] on redirections don’t send content related request headers (@xabbuh)
bug #45714 [Messenger] Fix cannot select FOR UPDATE from view on Oracle (@rjd22)
bug #45888 [Messenger] Add mysql indexes back and work around deadlocks using soft-delete (@nicolas-grekas)
bug #45891 [HttpClient] Fix exporting objects with readonly properties (@nicolas-grekas)
bug #45875 [ExpressionLanguage] Fix matches when the regexp is not valid (@fabpot)
bug #45870 [Validator] Fix File constraint invalid max size exception message (@fancyweb)
bug #45851 [Console] Fix exit status on uncaught exception with negative code (@acoulton)
bug #45838 [Serializer] Fix denormalizing union types (@T-bond)
bug #45816 [Mailer] Preserve case of headers (@nicolas-grekas)
bug #45814 [HttpClient] Let curl handle Content-Length headers (@nicolas-grekas)
bug #45813 [HttpClient] Move Content-Type after Content-Length (@nicolas-grekas)
bug #45737 [Lock] SemaphoreStore catching exception from sem_get (@Triplkrypl)
bug #45690 [Mailer] Use recipients in sendmail transport (@HypeMC)
bug #45720 [PropertyInfo] strip only leading when unknown docType (@EmilMassey)
bug #44915 [Console] Fix compact table style to avoid outputting a leading space (@Seldaek)
bug #45676 [Process] Don’t return executable directories in PhpExecutableFinder (@fancyweb)
bug #45702 [Form] Fix the usage of the Valid constraints in array-based forms (@stof)
bug #45677 [DependencyInjection] fix ServiceSubscriberTrait bug where parent has __call() (@kbond)
bug #45678 [HttpClient] Fix reading proxy settings from dotenv when curl is used (@nicolas-grekas)
bug #45671 [FrameworkBundle] Ensure container is reset between tests (@nicolas-grekas)

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.

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