Why Move Now
Vue 2 quietly slipped past its end-of-life date on December 31, 2023; it no longer receives security patches or browser-compat fixes.
At the same time, Vue 3.5 introduces a refactored reactivity core that reduces memory usage by 56% and accelerates large-array tracking by up to 10 times.
Every month you delay, you run a growing risk profile—unpatched CVEs, dwindling community plugins, and a shrinking talent pool that still wants to work in Options API land.
Business Payoff
- Lower cloud spend — Smaller bundles and tree-shaking reduce transfer and cold-start costs, especially on edge servers.
- Hiring advantage — Modern devs expect Composition API, TypeScript, and Vite-fast hot reloads
- Future-proof stack — Ecosystem libraries such as Pinia and Vue Router 4 are built for Vue 3 first and Vue 2 second (or not at all).
Staying on an unsupported core means paying a “legacy tax”—extra effort to keep old plugins alive or to negotiate extended LTS contracts from third parties.
Technical Gains You Can Measure
Migrating pays off on every performance front. A leaner runtime and faster template parser shave seconds off first paint and page transitions, while Vue 3’s built-in TypeScript types catch bugs before they ship.
Pinia replaces heavyweight Vuex with a lighter, composable store that’s TypeScript-first, and swapping Webpack for Vite brings hot-module reloads in under a second plus smaller production bundles.
Together, these upgrades cut cloud bills, reduce error rates, and make the developer experience feel instant.
A Road-Tested Migration Path
Switching major versions shouldn’t feel like walking a tightrope. The migration path below distills hard-won lessons from teams that have already crossed the gap, giving you a clear, repeatable sequence of moves that keeps momentum high and surprises low.
🛑 Freeze new features so your codebase isn’t a moving target
⬆️ Upgrade to Vue 2.7 and install the Composition API plugin—start rewriting new code in Composition style while tests still pass
🔍 Audit third-party packages; flag anything that lacks a Vue 3 branch
🔀 Decide rollout model
💥 Big-bang — re-platform in one sprint, suitable for small SPAs
🌳 Strangler-fig — mount Vue 3 micro-front-ends inside the legacy shell until 100 percent cut-over
Squeeze the Most out of Vue 2 First
Before you leap into Vue 3, give your Vue 2 codebase a quick tune-up. Cleaning up legacy patterns now will shrink your diff, surface hidden bugs, and make each migration commit painless.
🧹 Replace filters with computed props or methods
🔌 Remove global event buses ($on, $off) and migrate to a tiny emitter or provide/inject
🧩 Convert mixins into composables—this makes them easier to port later
🛡️ Bump your test coverage; every green spec serves as a guardrail for the upgrade
Lean on the Migration (Compat) Build
The @vue/compat bundle acts like a dual-personality runtime—Vue 3 under the hood, but it faithfully emulates most deprecated APIs. Enable it, ship it to staging, and watch the console light up with warnings. Fix warnings one by one until compatConfig: false shows zero hits. Then, swap to the pure vue package.
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Code-Level Cheat Sheet
The cheat sheet below pairs each familiar Vue 2 pattern with its Vue 3 replacement, turning guesswork into a quick copy-and-paste. Keep it open as you refactor—these one-to-one swaps will save hours of digging through docs.
🔄 Vue.use() → createApp().use()
🔄 Filters → computed or methods
🔄 Global mixins → composables (useAuth(), useTheme())
🔄 Vuex ≤ 4 → Pinia stores
🔄 vue-router 3 → vue-router 4 with Composition helpers such as useRouter() and useLink()
Modernize the Toolchain
Legacy tooling is often the hidden anchor that slows a migration more than the code itself. Updating the build, lint, and test stack upfront unlocks faster feedback loops and ensures every commit you make toward Vue 3 runs on the same modern foundation you’ll use in production.
🛠️ Move to Vite—the Vue team’s build tool—instant HMR and out-of-the-box SSR support
🛠️ Update ESLint to eslint-plugin-vue v9; enable the “migration” rule preset to catch Options-only patterns
🛠️ Swap Jest or Mocha for Vitest to keep the same Vite config in production and tests
🛠️ Adopt @vue/test-utils v2; it fully understands <script setup>
Performance You Can Show Your CFO
Cutting a few milliseconds off load time might sound trivial—until you multiply it across every session, every day, all year. Here’s how Vue 3 turns those micro-wins into line-item savings your CFO will appreciate.
🔥 20–30 percent smaller initial JS payloads thanks to tree-shaking Composition imports
🔥 Up to 2× faster SSR hydration on mid-tier devices
🔥 Lower long-task counts, meaning smoother scrolling on mobile
🔥 Instrument Core Web Vitals in production; faster Interaction-to-Next-Paint should be visible the day you flip the switch-Next-Paint should be visible the day you flip the switch
Common Pitfalls
Even the smoothest upgrade can hide a few landmines. Steer clear of these common migration pitfalls before they derail your timeline—or your production build.
⚠️ Forgetting to return reactive refs from setup—template can’t see them
⚠️ Custom directives renamed: bind/inserted → created/mounted
⚠️ Third-party UI libraries still on Vue 2—keep a fallback route or fork until maintainers catch up
⚠️ Misusing reactive ref values inside objects (refs unwrap in templates but not in JS)
Rollout and Monitoring Checklist
A migration is only as good as its launch. Follow this rollout and monitoring checklist to ship Vue 3 safely, spot issues early, and keep user experience—and error budgets—intact.
✅ Blue-green deploy behind a feature flag; route 1–5% of users to the Vue 3 build first
✅ Watch error budgets in your APM dashboard; look for spikes in TypeError: cannot read property 'value'
✅ Keep the last stable Vue 2 container image for at least 30 days as a safety net
✅ Run a post-launch retro and archive migration docs so future hires know the history
Ready-for-Launch Scorecard
Your code may build and tests may pass, but final confirmation takes more than green check marks. Run through this Ready-for-Launch Scorecard to be sure every box is ticked before you hit “deploy.”
🚀 All compat warnings resolved
🚀 Unit, e2e, and accessibility test suites green in CI
🚀 Build passes on Node 18 LTS
🚀 README and onboarding docs updated for Composition API
🚀 Team demo held and all questions answered
Vue 3 isn’t just a new syntax—it’s a faster runtime, a leaner bundle, and a signal to both customers and engineers that your product is built for the next five years, not the last five. The upgrade does take planning, but a structured approach turns it into a low-risk, high-reward project.
Need seasoned guides for your migration journey? Curotec’s front-end engineers have executed Vue 3 upgrades for SaaS, fintech, and enterprise portals alike. From audit and roadmap to hands-on refactoring and performance tuning, we do the heavy lifting while your team continues to ship features.
👉 Let’s talk about your Vue roadmap—reach out to Curotec today and start your upgrade on the right foot.
