From c0b26cada8225a3cb0531329bbab6209056ce6ae Mon Sep 17 00:00:00 2001
From: Raashish Aggarwal <94279692+raashish1601@users.noreply.github.com>
Date: Sat, 30 May 2026 17:13:41 +0530
Subject: [PATCH] fix(vue-query): avoid mounting QueryClient on server

---
 .../vue-query/src/__tests__/vueQueryPlugin.test.ts | 14 ++++++++++++++
 packages/vue-query/src/vueQueryPlugin.ts           |  4 ++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/packages/vue-query/src/__tests__/vueQueryPlugin.test.ts b/packages/vue-query/src/__tests__/vueQueryPlugin.test.ts
index cfcb18ce956..f7dce9073d5 100644
--- a/packages/vue-query/src/__tests__/vueQueryPlugin.test.ts
+++ b/packages/vue-query/src/__tests__/vueQueryPlugin.test.ts
@@ -1,5 +1,6 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import { isVue2, isVue3, ref } from 'vue-demi'
+import { environmentManager } from '@tanstack/query-core'
 import { queryKey } from '@tanstack/query-test-utils'
 import { QueryClient } from '../queryClient'
 import { VueQueryPlugin } from '../vueQueryPlugin'
@@ -218,6 +219,19 @@ describe('VueQueryPlugin', () => {
         customClient,
       )
     })
+
+    it('should not mount client when in a server environment', () => {
+      environmentManager.setIsServer(() => true)
+      try {
+        const appMock = getAppMock()
+        const customClient = { mount: vi.fn() } as unknown as QueryClient
+        VueQueryPlugin.install(appMock, { queryClient: customClient })
+
+        expect(customClient.mount).not.toHaveBeenCalled()
+      } finally {
+        environmentManager.setIsServer(() => false)
+      }
+    })
   })
 
   describe('when called with custom client config', () => {
diff --git a/packages/vue-query/src/vueQueryPlugin.ts b/packages/vue-query/src/vueQueryPlugin.ts
index 590d994d304..5c24bac18b7 100644
--- a/packages/vue-query/src/vueQueryPlugin.ts
+++ b/packages/vue-query/src/vueQueryPlugin.ts
@@ -1,5 +1,5 @@
 import { isVue2 } from 'vue-demi'
-import { isServer } from '@tanstack/query-core'
+import { environmentManager } from '@tanstack/query-core'
 
 import { QueryClient } from './queryClient'
 import { getClientKey } from './utils'
@@ -38,7 +38,7 @@ export const VueQueryPlugin = {
       client = new QueryClient(clientConfig)
     }
 
-    if (!isServer) {
+    if (!environmentManager.isServer()) {
       client.mount()
     }