diff --git a/dev-packages/e2e-tests/test-applications/react-router-8-framework/package.json b/dev-packages/e2e-tests/test-applications/react-router-8-framework/package.json
index 4cf3a981b6be..ad8fa7914f8d 100644
--- a/dev-packages/e2e-tests/test-applications/react-router-8-framework/package.json
+++ b/dev-packages/e2e-tests/test-applications/react-router-8-framework/package.json
@@ -11,6 +11,7 @@
     "@react-router/serve": "^8.0.0",
     "@sentry/bun": "file:../../packed/sentry-bun-packed.tgz",
     "@sentry/cloudflare": "file:../../packed/sentry-cloudflare-packed.tgz",
+    "@sentry/core": "file:../../packed/sentry-core-packed.tgz",
     "@sentry/deno": "file:../../packed/sentry-deno-packed.tgz",
     "@sentry/react-router": "file:../../packed/sentry-react-router-packed.tgz",
     "ioredis": "^5.11.1",
diff --git a/dev-packages/e2e-tests/test-applications/react-router-8-framework/tests/server-build.test.ts b/dev-packages/e2e-tests/test-applications/react-router-8-framework/tests/server-build.test.ts
new file mode 100644
index 000000000000..27dc4f31a025
--- /dev/null
+++ b/dev-packages/e2e-tests/test-applications/react-router-8-framework/tests/server-build.test.ts
@@ -0,0 +1,24 @@
+import { readdirSync, readFileSync } from 'node:fs';
+import path from 'node:path';
+import { expect, test } from '@playwright/test';
+import { bundleReferencesModule } from '@sentry-internal/test-utils';
+import { RUNTIME } from './constants';
+
+// `@sentry/core` is a direct dependency of this app so that Vite resolves it from the app root and
+// keeps it external, as in an npm install. Bundled into the server build, it hides the case where
+// bundled CommonJS `require()`s `@sentry/core`: Vite 5-7 turn that into a default import, and
+// `@sentry/core` has no default export, so the server crashes at startup.
+test.describe('server build', () => {
+  test.skip(RUNTIME === 'cloudflare', 'The Cloudflare build bundles all dependencies.');
+
+  test('imports the external @sentry/core by name only', () => {
+    const root = path.join(process.cwd(), 'build/server');
+    const serverBundle = readdirSync(root, { recursive: true, encoding: 'utf8' })
+      .filter(file => file.endsWith('.js'))
+      .map(file => readFileSync(path.join(root, file), 'utf8'))
+      .join('\n');
+
+    expect(bundleReferencesModule(serverBundle, '@sentry/core'), 'Vite must keep @sentry/core external').toBe(true);
+    expect(serverBundle.match(/\bimport\s+[\w$]+\s*(?:,\s*\{[^}]*\})?\s*from\s*["']@sentry\/[^"']+["']/g)).toBeNull();
+  });
+});
diff --git a/packages/server-utils/src/orchestrion/bundler/vite.ts b/packages/server-utils/src/orchestrion/bundler/vite.ts
index 0b8f66d961f4..c25552ac21cb 100644
--- a/packages/server-utils/src/orchestrion/bundler/vite.ts
+++ b/packages/server-utils/src/orchestrion/bundler/vite.ts
@@ -34,6 +34,11 @@ function ssrOnlyTransform(transform: Plugin['transform']): Plugin['transform'] {
   return transform;
 }
 
+// Maps the CJS entry of `@sentry/server-utils` to its ESM entry; any other id is returned unchanged.
+function toEsmEntry(id: string): string {
+  return id.replace(/([/\\])build[/\\]cjs[/\\]index\.js$/, '$1build$1esm$1index.js');
+}
+
 /**
  * Vite plugin that runs the orchestrion code transform on the bundled output.
  *
@@ -71,15 +76,21 @@ export function sentryOrchestrionPlugin(options: PluginOptions = {}): Plugin {
     // normal resolution fails, fall back to this package's own resolution so it
     // gets bundled from its real on-disk path. SSR-gated like the transform: the
     // specifier only appears in SSR modules.
+    //
+    // Always bundle the ESM entry. In a CommonJS module the snippet `require()`s the specifier,
+    // which resolves to the CJS build. Vite 5-7 turn that build's `require()`s of external
+    // packages into default imports, and `@sentry/core` has no default export, so the server
+    // crashes at startup. Vite 8 keeps the `require()`s, which loads a second copy of `@sentry/core`.
     async resolveId(source, importer, resolveOptions) {
       if (source !== SNIPPET_IMPORT_SPECIFIER || !resolveOptions?.ssr) {
         return null;
       }
       const resolved = await this.resolve(source, importer, { ...resolveOptions, skipSelf: true });
       if (resolved) {
-        return resolved;
+        return resolved.external ? resolved : { ...resolved, id: toEsmEntry(resolved.id) };
       }
-      return resolveOrchestrionRuntimeRequest(source) ?? null;
+      const fallback = resolveOrchestrionRuntimeRequest(source);
+      return fallback ? toEsmEntry(fallback) : null;
     },
     applyToEnvironment(environment) {
       // Orchestrion splices `node:diagnostics_channel` calls into instrumented modules, which only
diff --git a/packages/server-utils/test/orchestrion/bundler.test.ts b/packages/server-utils/test/orchestrion/bundler.test.ts
index b04fa7d1f160..07dc87d1c09b 100644
--- a/packages/server-utils/test/orchestrion/bundler.test.ts
+++ b/packages/server-utils/test/orchestrion/bundler.test.ts
@@ -348,6 +348,50 @@ describe('sentryOrchestrionPlugin (vite)', () => {
     expect(typeof fallback).toBe('string');
     expect(fallback).toContain('server-utils');
   });
+
+  it('resolves the snippet import to the ESM entry, also for require() calls', async () => {
+    const plugin = vitePlugin();
+    const resolveId = plugin.resolveId as (
+      this: unknown,
+      source: string,
+      importer: string | undefined,
+      opts?: { ssr?: boolean },
+    ) => Promise<unknown>;
+
+    const resolve = vi.fn().mockResolvedValue(null);
+    // How Vite 5-7 resolve a `require()` in a CommonJS module.
+    const requireOptions = { ssr: true, custom: { 'node-resolve': { isRequire: true } } };
+
+    resolve.mockResolvedValueOnce({
+      id: '/app/node_modules/@sentry/server-utils/build/cjs/index.js',
+      moduleSideEffects: false,
+    });
+    await expect(
+      resolveId.call({ resolve }, '@sentry/server-utils', '/app/node_modules/mysql/index.js', requireOptions),
+    ).resolves.toEqual({
+      id: '/app/node_modules/@sentry/server-utils/build/esm/index.js',
+      moduleSideEffects: false,
+    });
+    expect(resolve).toHaveBeenCalledWith('@sentry/server-utils', '/app/node_modules/mysql/index.js', {
+      ...requireOptions,
+      skipSelf: true,
+    });
+
+    resolve.mockResolvedValueOnce({ id: 'C:\\app\\node_modules\\@sentry\\server-utils\\build\\cjs\\index.js' });
+    await expect(resolveId.call({ resolve }, '@sentry/server-utils', '/x.js', requireOptions)).resolves.toEqual({
+      id: 'C:\\app\\node_modules\\@sentry\\server-utils\\build\\esm\\index.js',
+    });
+
+    resolve.mockResolvedValueOnce({ id: '@sentry/server-utils', external: true });
+    await expect(resolveId.call({ resolve }, '@sentry/server-utils', '/x.js', requireOptions)).resolves.toEqual({
+      id: '@sentry/server-utils',
+      external: true,
+    });
+
+    const fallback = await resolveId.call({ resolve }, '@sentry/server-utils', '/x.js', requireOptions);
+    expect(fallback).toMatch(/[/\\]build[/\\]esm[/\\]index\.js$/);
+    expect(existsSync(fallback as string)).toBe(true);
+  });
 });
 
 describe('sentryOrchestrionPlugin (bun)', () => {