diff --git a/packages/config/src/options.js b/packages/config/src/options.js
index b2e6bea3a9..3e064d20c6 100644
--- a/packages/config/src/options.js
+++ b/packages/config/src/options.js
@@ -237,7 +237,11 @@ export function getNuxtConfig(_options) {
 
   // Apply mode preset
   const modePreset = options.modes[options.mode || 'universal']
-  defaultsDeep(options, modePreset)
+
+  if (!modePreset) {
+    consola.warn(`Unknown mode: ${options.mode}. Falling back to universal`)
+  }
+  defaultsDeep(options, modePreset || options.modes.universal)
 
   if (options.modern === true) {
     options.modern = 'server'
diff --git a/test/fixtures/with-config/nuxt.config.js b/test/fixtures/with-config/nuxt.config.js
index f90a89e542..48ccb1e152 100644
--- a/test/fixtures/with-config/nuxt.config.js
+++ b/test/fixtures/with-config/nuxt.config.js
@@ -2,6 +2,7 @@ import path from 'path'
 import compression from 'compression'
 
 export default {
+  mode: 'unknown',
   srcDir: __dirname,
   server: {
     port: 8000,
diff --git a/test/fixtures/with-config/with-config.test.js b/test/fixtures/with-config/with-config.test.js
index c3f1b20bb2..6d1b6da61c 100644
--- a/test/fixtures/with-config/with-config.test.js
+++ b/test/fixtures/with-config/with-config.test.js
@@ -14,9 +14,12 @@ const hooks = [
 
 describe('with-config', () => {
   buildFixture('with-config', () => {
-    expect(consola.warn).toHaveBeenCalledTimes(3)
+    expect(consola.warn).toHaveBeenCalledTimes(4)
     expect(consola.fatal).toHaveBeenCalledTimes(0)
     expect(consola.warn.mock.calls).toMatchObject([
+      [
+        'Unknown mode: unknown. Falling back to universal'
+      ],
       [{
         message: 'Found 2 plugins that match the configuration, suggest to specify extension:',
         additional: expect.stringContaining('plugins/test.json')