diff --git a/app/package.json b/app/package.json
index 9a20cdf0..17ce6d94 100644
--- a/app/package.json
+++ b/app/package.json
@@ -21,7 +21,7 @@
     "fork-awesome": "^1.2.0",
     "simple-evaluate": "^1.4.6",
     "vue": "3.3.4",
-    "vue-i18n": "^8.28.2",
+    "vue-i18n": "^9.10.1",
     "vue-router": "^4.3.0",
     "vue-showdown": "^2.4.1",
     "vuex": "^4.1.0"
diff --git a/app/src/api/errors.js b/app/src/api/errors.js
index 066c02d8..af2f5317 100644
--- a/app/src/api/errors.js
+++ b/app/src/api/errors.js
@@ -10,7 +10,7 @@ class APIError extends Error {
     super(
       error
         ? error.replaceAll('\n', '<br>')
-        : i18n.t('error_server_unexpected'),
+        : i18n.global.t('error_server_unexpected'),
     )
     const urlObj = new URL(url)
     this.name = 'APIError'
@@ -39,7 +39,9 @@ class APIErrorLog extends APIError {
 // 0 — (means "the connexion has been closed" apparently)
 class APIConnexionError extends APIError {
   constructor(method, response) {
-    super(method, response, { error: i18n.t('error_connection_interrupted') })
+    super(method, response, {
+      error: i18n.global.t('error_connection_interrupted'),
+    })
     this.name = 'APIConnexionError'
   }
 }
@@ -57,7 +59,7 @@ class APIBadRequestError extends APIError {
 // 401 — Unauthorized
 class APIUnauthorizedError extends APIError {
   constructor(method, response, errorData) {
-    super(method, response, { error: i18n.t('unauthorized') })
+    super(method, response, { error: i18n.global.t('unauthorized') })
     this.name = 'APIUnauthorizedError'
   }
 }
@@ -65,7 +67,7 @@ class APIUnauthorizedError extends APIError {
 // 404 — Not Found
 class APINotFoundError extends APIError {
   constructor(method, response, errorData) {
-    errorData.error = i18n.t('api_not_found')
+    errorData.error = i18n.global.t('api_not_found')
     super(method, response, errorData)
     this.name = 'APINotFoundError'
   }
@@ -83,7 +85,7 @@ class APIInternalError extends APIError {
 // 502 — Bad gateway (means API is down)
 class APINotRespondingError extends APIError {
   constructor(method, response) {
-    super(method, response, { error: i18n.t('api_not_responding') })
+    super(method, response, { error: i18n.global.t('api_not_responding') })
     this.name = 'APINotRespondingError'
   }
 }
diff --git a/app/src/helpers/yunohostArguments.js b/app/src/helpers/yunohostArguments.js
index ece0a1fc..bba66f7f 100644
--- a/app/src/helpers/yunohostArguments.js
+++ b/app/src/helpers/yunohostArguments.js
@@ -152,7 +152,7 @@ export function formatYunoHostArgument(arg) {
       props: defaultProps.concat(['type', 'autocomplete', 'trim']),
       callback: function () {
         if (!arg.help) {
-          arg.help = i18n.t('good_practices_about_admin_password')
+          arg.help = i18n.global.t('good_practices_about_admin_password')
         }
         arg.example = '••••••••••••'
         validation.passwordLenght = validators.minLength(8)
@@ -180,7 +180,7 @@ export function formatYunoHostArgument(arg) {
         if (arg.type !== 'select') {
           field.props.link = {
             name: arg.type + '-list',
-            text: i18n.t(`manage_${arg.type}s`),
+            text: i18n.global.t(`manage_${arg.type}s`),
           }
         }
       },
@@ -337,7 +337,7 @@ export function formatYunoHostArgument(arg) {
   if (arg.helpLink) {
     field.props.link = {
       href: arg.helpLink.href,
-      text: i18n.t(arg.helpLink.text),
+      text: i18n.global.t(arg.helpLink.text),
     }
   }
 
diff --git a/app/src/i18n/helpers.js b/app/src/i18n/helpers.js
index cd0b7117..1899f1ca 100644
--- a/app/src/i18n/helpers.js
+++ b/app/src/i18n/helpers.js
@@ -1,9 +1,9 @@
+import { nextTick } from 'vue'
 import store from '@/store'
 import i18n from '@/i18n'
 import supportedLocales from './supportedLocales'
 
-let dateFnsLocale
-const loadedLanguages = []
+export let dateFnsLocale
 
 /**
  * Returns the first two supported locales that can be found in the `localStorage` or
@@ -34,26 +34,54 @@ function getDefaultLocales() {
   return defaultLocales
 }
 
-function updateDocumentLocale(locale) {
-  document.documentElement.lang = locale
+export async function setI18nLocale(locale) {
+  if (!i18n.global.availableLocales.includes(locale)) {
+    await loadLocaleMessages(locale)
+    // also query/set the date-fns locale object for time translation
+    await loadDateFnsLocale(locale)
+  }
+
+  // Preload 'en' locales as it is the hard fallback
+  if (locale !== 'en' && !i18n.global.availableLocales.includes('en')) {
+    loadLocaleMessages('en')
+  }
+
+  if (i18n.mode === 'legacy') {
+    i18n.global.locale = locale
+  } else {
+    i18n.global.locale.value = locale
+  }
+
+  document.querySelector('html').setAttribute('lang', locale)
   // FIXME can't currently change document direction easily since bootstrap still doesn't handle rtl.
   // document.dir = locale === 'ar' ? 'rtl' : 'ltr'
 }
 
+export async function setI18nFallbackLocale(locale) {
+  if (!i18n.global.availableLocales.includes(locale)) {
+    await loadLocaleMessages(locale)
+  }
+
+  if (i18n.mode === 'legacy') {
+    i18n.global.fallbackLocale = [locale, 'en']
+  } else {
+    i18n.global.fallbackLocale.value = [locale, 'en']
+  }
+}
+
 /**
  * Loads a translation file and adds its content to the i18n plugin `messages`.
  *
  * @return {Promise<string>} Promise that resolve the given locale string
  */
-function loadLocaleMessages(locale) {
-  if (loadedLanguages.includes(locale)) {
-    return Promise.resolve(locale)
-  }
-  return import(`@/i18n/locales/${locale}.json`).then((messages) => {
-    i18n.setLocaleMessage(locale, messages.default)
-    loadedLanguages.push(locale)
-    return locale
-  })
+export async function loadLocaleMessages(locale) {
+  // load locale messages with dynamic import
+  const messages = await import(`./locales/${locale}.json`)
+
+  // set locale and locale message
+  i18n.global.setLocaleMessage(locale, messages)
+
+  return nextTick()
 }
 
 /**
@@ -71,19 +99,10 @@ async function loadDateFnsLocale(locale) {
 /**
  * Initialize all locales
  */
-function initDefaultLocales() {
+export async function initDefaultLocales() {
   // Get defined locales from `localStorage` or `navigator`
   const [locale, fallbackLocale] = getDefaultLocales()
 
-  store.dispatch('UPDATE_LOCALE', locale)
-  store.dispatch('UPDATE_FALLBACKLOCALE', fallbackLocale || 'en')
-  return loadLocaleMessages('en')
-}
-
-export {
-  initDefaultLocales,
-  updateDocumentLocale,
-  loadLocaleMessages,
-  loadDateFnsLocale,
-  dateFnsLocale,
+  await store.dispatch('UPDATE_LOCALE', locale)
+  await store.dispatch('UPDATE_FALLBACKLOCALE', fallbackLocale || 'en')
 }
diff --git a/app/src/i18n/index.js b/app/src/i18n/index.js
index f575be80..df48cfc5 100644
--- a/app/src/i18n/index.js
+++ b/app/src/i18n/index.js
@@ -3,10 +3,9 @@
  * @module i18n
  */
 
-import Vue from 'vue'
-import VueI18n from 'vue-i18n'
+import { createI18n } from 'vue-i18n'
 
-// Plugin Initialization
-Vue.use(VueI18n)
-
-export default new VueI18n({})
+export default createI18n({
+  // FIXME
+  legacy: true,
+})
diff --git a/app/src/store/info.js b/app/src/store/info.js
index 5bc5ce3f..fc6698bc 100644
--- a/app/src/store/info.js
+++ b/app/src/store/info.js
@@ -199,7 +199,7 @@ export default {
         ? humanKey
         : { key: humanKey }
       const humanRoute = key
-        ? i18n.t('human_routes.' + key, args)
+        ? i18n.global.t('human_routes.' + key, args)
         : `[${method}] /${uri}`
 
       let request = {
@@ -368,9 +368,9 @@ export default {
         // if a traduction key string has been given and we also need to pass
         // the route param as a variable.
         if (trad && param) {
-          text = i18n.t(trad, { [param]: to.params[param] })
+          text = i18n.global.t(trad, { [param]: to.params[param] })
         } else if (trad) {
-          text = i18n.t(trad)
+          text = i18n.global.t(trad)
         } else {
           text = to.params[param]
         }
@@ -395,7 +395,7 @@ export default {
       }
 
       // Display a simplified breadcrumb as the document title.
-      document.title = `${getTitle(breadcrumb)} | ${i18n.t('yunohost_admin')}`
+      document.title = `${getTitle(breadcrumb)} | ${i18n.global.t('yunohost_admin')}`
     },
 
     UPDATE_TRANSITION_NAME({ state, commit }, { to, from }) {
diff --git a/app/src/store/settings.js b/app/src/store/settings.js
index a67e98d0..68ba324c 100644
--- a/app/src/store/settings.js
+++ b/app/src/store/settings.js
@@ -3,12 +3,7 @@
  * @module store/settings
  */
 
-import i18n from '@/i18n'
-import {
-  loadLocaleMessages,
-  updateDocumentLocale,
-  loadDateFnsLocale,
-} from '@/i18n/helpers'
+import { setI18nLocale, setI18nFallbackLocale } from '@/i18n/helpers'
 import supportedLocales from '@/i18n/supportedLocales'
 
 export default {
@@ -62,19 +57,14 @@ export default {
 
   actions: {
     UPDATE_LOCALE({ commit }, locale) {
-      loadLocaleMessages(locale).then(() => {
-        updateDocumentLocale(locale)
+      return setI18nLocale(locale).then(() => {
         commit('SET_LOCALE', locale)
-        i18n.locale = locale
       })
-      // also query the date-fns locale object for filters
-      loadDateFnsLocale(locale)
     },
 
     UPDATE_FALLBACKLOCALE({ commit }, locale) {
-      loadLocaleMessages(locale).then(() => {
+      return setI18nFallbackLocale(locale).then(() => {
         commit('SET_FALLBACKLOCALE', locale)
-        i18n.fallbackLocale = [locale, 'en']
       })
     },
 
diff --git a/app/vite.config.js b/app/vite.config.js
index ae773995..01fb6825 100644
--- a/app/vite.config.js
+++ b/app/vite.config.js
@@ -3,6 +3,14 @@ import { defineConfig, loadEnv } from 'vite'
 import fs from 'fs'
 import createVuePlugin from '@vitejs/plugin-vue'
 
+import supportedLocales from './src/i18n/supportedLocales'
+
+const supportedDatefnsLocales = Object.entries(supportedLocales).map(
+  ([locale, { dateFnsLocale }]) => {
+    return dateFnsLocale || locale
+  },
+)
+
 export default defineConfig(({ command, mode }) => {
   // Load env file based on `mode` in the current working directory.
   // Set the third parameter to '' to load all env regardless of the `VITE_` prefix.
@@ -53,6 +61,28 @@ export default defineConfig(({ command, mode }) => {
             if (!id.includes('node_modules') && id.includes('api/')) {
               return 'core'
             }
+            // Translations
+            if (id.includes('locales')) {
+              const match = /.*\/i18n\/locales\/([\w-]+)\.json/.exec(id)
+              return `locales/${match[1]}/translations`
+            }
+            // Split date-fns locales
+            if (id.includes('date-fns')) {
+              const match = /.*\/date-fns\/esm\/locale\/([\w-]+)\/.*\.js/.exec(
+                id,
+              )
+              if (match) {
+                if (supportedDatefnsLocales.includes(match[1])) {
+                  return `locales/${match[1]}/date-fns`
+                } else {
+                  // FIXME: currently difficult to cherry pick only needed locales,
+                  // hopefully this chunk should not be fetched.
+                  return 'locales/not-used'
+                }
+              } else {
+                return 'date-fns'
+              }
+            }
           },
         },
       },