externals not existing on nitro 3

Author: s1gr1d

packages/nuxt/src/vite/addServerConfig.ts

@@ -160,10 +160,13 @@ export function addServerConfigPlugin(nuxt: Nuxt, serverConfigFile: string, isLe
 
     // The Nitro v2 dev bundle would otherwise externalize these files, making Node load the raw
     // `.ts` config — which needs type stripping (Node >= 22.18). Inlining keeps them transpiled.
-    const externals = (nitroConfig.externals ??= {});
-    const inline = externals.inline;
-    const existingInline = Array.isArray(inline) ? inline : inline ? [inline] : [];
-    externals.inline = [...existingInline, configPath, configPluginTemplate.dst, runtimeFlagsTemplate.dst];
+    // Nitro v3 has no `externals` option; its dev server runs the config through Vite's transform.
+    if (isLegacyNitro) {
+      const externals = (nitroConfig.externals ??= {});
+      const inline = externals.inline;
+      const existingInline = Array.isArray(inline) ? inline : inline ? [inline] : [];
+      externals.inline = [...existingInline, configPath, configPluginTemplate.dst, runtimeFlagsTemplate.dst];
+    }
   });
 
   // On Cloudflare the SDK is set up through `sentryCloudflareNitroPlugin`; the Node SDK config

packages/nuxt/test/vite/addServerConfig.test.ts

@@ -208,6 +208,18 @@ describe('addServerConfigPlugin', () => {
     expect(nitroConfig.externals?.inline).toEqual(['@sentry/', APP_CONFIG, pluginDst, flagsDst]);
   });
 
+  it('leaves `externals` alone on Nitro v3, which has no such option', () => {
+    const { nuxt, hooks } = createFakeNuxt();
+    addServerConfigPlugin(nuxt, APP_CONFIG, false);
+    const nitroConfig: NitroConfig = { plugins: ['other-module-plugin.mjs'] };
+
+    hooks['nitro:config']!(nitroConfig);
+
+    expect(nitroConfig.externals).toBeUndefined();
+    // Plugin ordering is not Nitro-version specific and still applies.
+    expect(nitroConfig.plugins).toEqual([pluginDst, 'other-module-plugin.mjs']);
+  });
+
   it('moves its plugin to the front when other modules registered plugins first', () => {
     const { nuxt, hooks } = createFakeNuxt();
     addServerConfigPlugin(nuxt, APP_CONFIG, true);