diff --git a/packages/shared/src/index.ts b/packages/shared/src/index.ts
index 87c19dfd7..4b4946525 100644
--- a/packages/shared/src/index.ts
+++ b/packages/shared/src/index.ts
@@ -3,3 +3,4 @@ export * from './warn'
 export * from './error'
 export * from './emittable'
 export * from './emitter'
+export * from './messages'
diff --git a/packages/shared/src/messages.ts b/packages/shared/src/messages.ts
new file mode 100644
index 000000000..69172dd93
--- /dev/null
+++ b/packages/shared/src/messages.ts
@@ -0,0 +1,24 @@
+import { hasOwn, isArray, isObject } from './utils'
+
+const isNotObjectOrIsArray = (val: unknown) => !isObject(val) || isArray(val)
+// eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/explicit-module-boundary-types
+export function deepCopy(src: any, des: any): void {
+  // src and des should both be objects, and none of them can be a array
+  if (isNotObjectOrIsArray(src) || isNotObjectOrIsArray(des)) {
+    throw new Error('Invalid value')
+  }
+
+  for (const key in src) {
+    if (hasOwn(src, key)) {
+      if (isNotObjectOrIsArray(src[key]) || isNotObjectOrIsArray(des[key])) {
+        // replace with src[key] when:
+        // src[key] or des[key] is not an object, or
+        // src[key] or des[key] is an array
+        des[key] = src[key]
+      } else {
+        // src[key] and des[key] are both objects, merge them
+        deepCopy(src[key], des[key])
+      }
+    }
+  }
+}
diff --git a/packages/vue-i18n-core/src/composer.ts b/packages/vue-i18n-core/src/composer.ts
index c730179cf..7c8a3e67c 100644
--- a/packages/vue-i18n-core/src/composer.ts
+++ b/packages/vue-i18n-core/src/composer.ts
@@ -12,6 +12,7 @@ import {
   isObject,
   assign,
   inBrowser,
+  deepCopy,
   hasOwn
 } from '@intlify/shared'
 import {
@@ -53,7 +54,6 @@ import {
   __VUE_I18N_BRIDGE__
 } from './symbols'
 import {
-  deepCopy,
   getLocaleMessages,
   getComponentOptions,
   createTextNode,
diff --git a/packages/vue-i18n-core/src/mixins/bridge.ts b/packages/vue-i18n-core/src/mixins/bridge.ts
index c49eeaa13..564085435 100644
--- a/packages/vue-i18n-core/src/mixins/bridge.ts
+++ b/packages/vue-i18n-core/src/mixins/bridge.ts
@@ -1,5 +1,4 @@
-import { isPlainObject, warn } from '@intlify/shared'
-import { deepCopy } from '../utils'
+import { deepCopy, isPlainObject, warn } from '@intlify/shared'
 
 import type { ComponentOptions } from 'vue'
 import type { Locale } from '@intlify/core-base'
diff --git a/packages/vue-i18n-core/src/utils.ts b/packages/vue-i18n-core/src/utils.ts
index 6af257bf6..a7291268c 100644
--- a/packages/vue-i18n-core/src/utils.ts
+++ b/packages/vue-i18n-core/src/utils.ts
@@ -5,10 +5,10 @@ import {
   hasOwn,
   isPlainObject,
   isString,
+  deepCopy,
   warn
 } from '@intlify/shared'
 import { Text, createVNode } from 'vue'
-import { I18nErrorCodes, createI18nError } from './errors'
 import { I18nWarnCodes, getWarnMessage } from './warnings'
 
 import type { Locale, MessageResolver } from '@intlify/core-base'
@@ -148,29 +148,6 @@ export function getLocaleMessages<Messages = {}>(
   return ret as { [K in keyof Messages]: Messages[K] }
 }
 
-const isNotObjectOrIsArray = (val: unknown) => !isObject(val) || isArray(val)
-// eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/explicit-module-boundary-types
-export function deepCopy(src: any, des: any): void {
-  // src and des should both be objects, and non of then can be a array
-  if (isNotObjectOrIsArray(src) || isNotObjectOrIsArray(des)) {
-    throw createI18nError(I18nErrorCodes.INVALID_VALUE)
-  }
-
-  for (const key in src) {
-    if (hasOwn(src, key)) {
-      if (isNotObjectOrIsArray(src[key]) || isNotObjectOrIsArray(des[key])) {
-        // replace with src[key] when:
-        // src[key] or des[key] is not a object, or
-        // src[key] or des[key] is a array
-        des[key] = src[key]
-      } else {
-        // src[key] and des[key] are both object, merge them
-        deepCopy(src[key], des[key])
-      }
-    }
-  }
-}
-
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export function getComponentOptions(instance: ComponentInternalInstance): any {
   return !__BRIDGE__ ? instance.type : instance.proxy!.$options