diff --git a/dev-packages/e2e-tests/test-applications/tanstackstart-react-cloudflare/package.json b/dev-packages/e2e-tests/test-applications/tanstackstart-react-cloudflare/package.json
index 5cf6accf0cd1..688094b3d237 100644
--- a/dev-packages/e2e-tests/test-applications/tanstackstart-react-cloudflare/package.json
+++ b/dev-packages/e2e-tests/test-applications/tanstackstart-react-cloudflare/package.json
@@ -28,10 +28,10 @@
     "@sentry-internal/test-utils": "link:../../../test-utils",
     "@types/react": "^19.2.0",
     "@types/react-dom": "^19.2.0",
-    "@vitejs/plugin-react": "^4.5.0",
+    "@vitejs/plugin-react": "^6.1.2",
     "typescript": "^5.9.0",
-    "vite": "7.3.2",
-    "vite-tsconfig-paths": "^5.1.4",
+    "vite": "8.3.4",
+    "vite-tsconfig-paths": "^6.1.1",
     "wrangler": "^4.68.1"
   },
   "volta": {
diff --git a/dev-packages/e2e-tests/test-applications/tanstackstart-react/package.json b/dev-packages/e2e-tests/test-applications/tanstackstart-react/package.json
index 89dad11c3985..410f41baecbc 100644
--- a/dev-packages/e2e-tests/test-applications/tanstackstart-react/package.json
+++ b/dev-packages/e2e-tests/test-applications/tanstackstart-react/package.json
@@ -14,7 +14,7 @@
     "test:build:tunnel-static": "pnpm install && E2E_TEST_TUNNEL_ROUTE_MODE=static E2E_TEST_DSN=http://public@localhost:3031/1337 pnpm build",
     "test:build:tunnel-custom": "pnpm install && E2E_TEST_CUSTOM_TUNNEL_ROUTE=1 pnpm build",
     "test:build:tunnel-object": "pnpm install && E2E_TEST_TUNNEL_ROUTE_MODE=object E2E_TEST_DSN=http://public@localhost:3031/1337 pnpm build",
-    "test:build-latest": "pnpm add @tanstack/react-start@latest @tanstack/react-router@latest && pnpm install && pnpm build",
+    "test:build-latest": "pnpm add @tanstack/react-start@latest @tanstack/react-router@latest nitro@latest vite@latest @vitejs/plugin-react-swc@latest vite-tsconfig-paths@latest && pnpm install && pnpm build",
     "test:assert:proxy": "pnpm test && TEST_ENV=development pnpm playwright test db-drivers",
     "test:assert": "pnpm test:assert:proxy",
     "test:assert:tunnel-generated": "E2E_TEST_TUNNEL_ROUTE_MODE=dynamic E2E_TEST_DSN=http://public@localhost:3031/1337 pnpm test",
diff --git a/packages/tanstackstart-react/src/vite/routePatterns.ts b/packages/tanstackstart-react/src/vite/routePatterns.ts
index 5ffbdaa83c52..82a187d08e70 100644
--- a/packages/tanstackstart-react/src/vite/routePatterns.ts
+++ b/packages/tanstackstart-react/src/vite/routePatterns.ts
@@ -19,6 +19,16 @@ export function makeRoutePatternPlugin(): Plugin {
     name: 'sentry-tanstackstart-route-patterns',
     enforce: 'post',
 
+    // The transform below must see the SDK's own `wrapFetchWithSentry` file. Vite externalizes dependencies in
+    // server builds, and Nitro 3 copies external dependencies into its output instead of bundling them.
+    configEnvironment(name, config, env) {
+      if (env.command === 'serve' || (config.consumer ?? (name === 'client' ? 'client' : 'server')) !== 'server') {
+        return null;
+      }
+
+      return { resolve: { noExternal: ['@sentry/tanstackstart-react'] } };
+    },
+
     configResolved(config) {
       resolvedRoot = config.root || process.cwd();
     },
diff --git a/packages/tanstackstart-react/test/vite/routePatterns.test.ts b/packages/tanstackstart-react/test/vite/routePatterns.test.ts
index 413b29adafe1..abc5c92527d9 100644
--- a/packages/tanstackstart-react/test/vite/routePatterns.test.ts
+++ b/packages/tanstackstart-react/test/vite/routePatterns.test.ts
@@ -2,7 +2,30 @@ import * as fs from 'node:fs';
 import * as os from 'node:os';
 import * as path from 'node:path';
 import { afterEach, beforeEach, describe, expect, it } from 'vitest';
-import { extractRoutePatterns, findRouteTreeFile } from '../../src/vite/routePatterns';
+import { extractRoutePatterns, findRouteTreeFile, makeRoutePatternPlugin } from '../../src/vite/routePatterns';
+
+describe('makeRoutePatternPlugin', () => {
+  const configEnvironment = makeRoutePatternPlugin().configEnvironment as (
+    name: string,
+    config: { consumer?: 'client' | 'server' },
+    env: { command: 'build' | 'serve'; mode: string },
+  ) => { resolve: { noExternal: string[] } } | null;
+
+  it('bundles the SDK into server environments of a build', () => {
+    const build = { command: 'build', mode: 'production' } as const;
+
+    expect(configEnvironment('ssr', {}, build)).toEqual({ resolve: { noExternal: ['@sentry/tanstackstart-react'] } });
+    expect(configEnvironment('nitro', { consumer: 'server' }, build)).toEqual({
+      resolve: { noExternal: ['@sentry/tanstackstart-react'] },
+    });
+  });
+
+  it('does not change client environments or the dev server', () => {
+    expect(configEnvironment('client', {}, { command: 'build', mode: 'production' })).toBeNull();
+    expect(configEnvironment('ssr', { consumer: 'client' }, { command: 'build', mode: 'production' })).toBeNull();
+    expect(configEnvironment('ssr', {}, { command: 'serve', mode: 'development' })).toBeNull();
+  });
+});
 
 describe('extractRoutePatterns', () => {
   it('extracts full path patterns from single-line fullPaths union', () => {