Java Backend Technology

Oct 29, 2025 · Backend Development

Why Spring Boot 4.0 Dropped Undertow Support and What It Means for Your Projects

Spring Boot 4.0 RC1 removes Undertow support because it cannot meet the Servlet 6.1 baseline, forcing developers to migrate web containers, and the article explains the technical reasons, new Servlet 6.1 features, Jakarta EE 11 changes, compatibility matrix, and migration guidance.