Symfony 8.1.1

⚡ Symfony 8.1.1 just dropped — June 27, 2026 — and it comes packed with bug bashes, ObjectMapper overhauls, and compatibility corrections. This first patch since the 8.1.0 feature release (May 29) addresses over 50 issues, with a strong focus on the new ObjectMapper component and cache interoperability.

🔧 ObjectMapper Overhaul

The ObjectMapper component, introduced in Symfony 8.1, receives substantial bug fixes in this release. Self-referencing property mapping, private properties from parent classes, and reverse class mapping with unreadable sources all get attention. The team at @nicolas-grekas and @soyuka have made existing-object mapping behavior consistent across all call sites.

• Fix self-referencing property mapping (#64589)
• Fix private properties from parent classes in reverse class map (#63791)
• Fix fatal errors on unreadable source properties (#64584)
• Handle N targets per source in reverse class map (#64567)

🔐 Security Hardening

Multiple unserialize-related hardening patches land in this release. __toString trampolines are reinforced via __unserialize(), and the HttpKernel component adds allowed_classes => false guards to unserialize() calls in CacheWarmerAggregate, LoggerDataCollector, and HttpCache Store.

• Harden __toString trampolines via __unserialize() (#64566)
• TwigBridge rejects __toString trampolines in TemplatedEmail (#64549)
• Allowed-classes hardening in CacheWarmer, LoggerDataCollector, HttpCache (#64419)

🐛 Bug Bashes

Serializer fixes lead the charge: GetSetMethodNormalizer now correctly denormalizes constructor-only objects, the #[Ignore] attribute no longer conflicts with same-name property getters, and csv_headers context is honored when no_headers is true. The Finder component gains proper Windows stream wrapper recursion.

• Serializer: Fix #[Ignore] on getters conflicting with properties (#64225)
• Cache: RelayProxy and RelayClusterProxy compatibility with Relay 0.30.0 (#64648, #64645)
• Messenger: Redis listable capabilities fix (#64640)
• AssetMapper: Fix stale dev asset cache in long-running runtimes (#64635)
• Form: Don't re-add deleted collection entries on submit (#64536)

🆙 Upgrade at Your Pace

Symfony 8.1.1 is a standard patch release with no breaking changes. To upgrade, update your composer.json constraints to ^8.1 and run composer update. Review the CHANGELOG-8.1.md for the full diff if you rely on any of the affected components.

⬆️ Don't delay the upgrade — this release patches real regressions and keeps your Symfony stack fresh.