diff --git a/packages/@vue/cli-service/__tests__/serve.spec.js b/packages/@vue/cli-service/__tests__/serve.spec.js
index 2972c681fb..366309eba0 100644
--- a/packages/@vue/cli-service/__tests__/serve.spec.js
+++ b/packages/@vue/cli-service/__tests__/serve.spec.js
@@ -181,7 +181,7 @@ test('dart sass', async () => {
   await project.run('vue-cli-service build')
 })
 
-test.only('use a single websocket connection for HMR', async () => {
+test('use a single websocket connection for HMR', async () => {
   const project = await create('e2e-serve', defaultPreset)
 
   await serve(
diff --git a/packages/@vue/cli-service/lib/commands/serve.js b/packages/@vue/cli-service/lib/commands/serve.js
index 2b7dbfb801..f08df1ac8b 100644
--- a/packages/@vue/cli-service/lib/commands/serve.js
+++ b/packages/@vue/cli-service/lib/commands/serve.js
@@ -172,6 +172,7 @@ module.exports = (api, options) => {
       contentBase: api.resolve('public'),
       watchContentBase: !isProduction,
       hot: !isProduction,
+      injectClient: false,
       compress: isProduction,
       publicPath: options.publicPath,
       overlay: isProduction // TODO disable this