# Fastify v5 breaking changes: should you upgrade?

DevFeed: [Fastify v5 breaking changes: should you upgrade?](<https://devfeed.tech/articles/fastify-v5-breaking-changes-should-you-upgrade-17798.md>)

Original publisher: [Read original article](<https://encore.dev/blog/fastify-v5>)

Author: André Eriksson

Published: 2024-09-17T00:00:00Z

Content type: opinion

Language: en

Sources: [Encore Updates](<https://devfeed.tech/sources/encore-updates.md>)

Topics: [Fastify](<https://devfeed.tech/topics/fastify.md>), [Framework](<https://devfeed.tech/topics/framework.md>), [benchmarking](<https://devfeed.tech/topics/benchmarking.md>)

Tags: [deprecated](<https://devfeed.tech/tags/deprecated.md>), [migration-guide](<https://devfeed.tech/tags/migration-guide.md>), [performance](<https://devfeed.tech/tags/performance.md>), [release](<https://devfeed.tech/tags/release.md>), [upgrade](<https://devfeed.tech/tags/upgrade.md>)

## AI overview

This opinion article examines Fastify v5 and argues that upgrading may not be worthwhile for most users. It highlights roughly 20 breaking changes, reduced convenience in JSON Schema definitions, sparse documentation about upgrade benefits, support for the Diagnostic Channel API, and a reported 5-10% performance improvement over v4 depending on configuration and schema validation.

## Source excerpt

Spoiler alert: probably not.