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Jan 7, 2026 · Backend Development

Step‑by‑Step Guide to Upgrade Spring Boot 3.x to 4.0 Without Pain

This guide walks through upgrading a Spring Boot 3.x project to 4.0, covering Gradle version bump, dependency version catalog updates, modular starter changes, the breaking Jackson 3 package rename, Redisson API adjustments, verification steps, and best‑practice upgrade path to avoid common pitfalls.