# Out with the Old, In with the New: A Guide to Application Upkeep

DevFeed: [Out with the Old, In with the New: A Guide to Application Upkeep](<https://devfeed.tech/articles/out-with-the-old-in-with-the-new-a-guide-to-application-upkeep-23026.md>)

Original publisher: [Read original article](<https://www.javaadvent.com/2025/12/out-with-the-old-in-with-the-new.html>)

Author: Andres Sacco

Published: 2025-12-20T03:08:59Z

Content type: tutorial

Language: en

Sources: [Java Advent Calendar](<https://devfeed.tech/sources/java-advent-calendar.md>)

Topics: [Java](<https://devfeed.tech/topics/java.md>), [migration](<https://devfeed.tech/topics/migration.md>), [Spring Boot](<https://devfeed.tech/topics/spring-boot.md>), [Microservice](<https://devfeed.tech/topics/microservice.md>), [Vulnerabilities](<https://devfeed.tech/topics/vulnerabilities.md>), [Security](<https://devfeed.tech/topics/security.md>)

Tags: [2025](<https://devfeed.tech/tags/2025.md>), [automatic](<https://devfeed.tech/tags/automatic.md>), [guide](<https://devfeed.tech/tags/guide.md>), [java](<https://devfeed.tech/tags/java.md>), [legacy-application](<https://devfeed.tech/tags/legacy-application.md>), [legacy-code](<https://devfeed.tech/tags/legacy-code.md>), [maintainability](<https://devfeed.tech/tags/maintainability.md>), [microservices](<https://devfeed.tech/tags/microservices.md>), [migration](<https://devfeed.tech/tags/migration.md>), [rewrite](<https://devfeed.tech/tags/rewrite.md>), [security](<https://devfeed.tech/tags/security.md>), [spring](<https://devfeed.tech/tags/spring.md>), [spring-boot](<https://devfeed.tech/tags/spring-boot.md>)

## AI overview

This guide explains why upgrading Java or Spring Boot applications involves more than changing a version number. It discusses migration challenges, legacy code, differing versions across microservices, and risks from outdated software, including security, compatibility, stability, and maintainability concerns.

## Source excerpt

Migrating an existing application to a new version of Java or a framework such as Spring Boot involves much more than simply updating a version number in a file. Each new release of a library or language brings new features, deprecations, behavioral changes, and sometimes complete API redesigns. When legacy code is involved, these upgrades [...] The post Out with the Old, In with the New: A Guide to Application Upkeep appeared first on JVM Advent.