diff --git a/packages/app/src/cli/services/deploy/bundle.test.ts b/packages/app/src/cli/services/deploy/bundle.test.ts
index e30d3e091fc..78aa958d5fa 100644
--- a/packages/app/src/cli/services/deploy/bundle.test.ts
+++ b/packages/app/src/cli/services/deploy/bundle.test.ts
@@ -256,7 +256,7 @@ describe('bundleAndBuildExtensions', () => {
     })
   })
 
-  test('runs web build command concurrently with extensions when build command is defined', async () => {
+  test('runs web build before extensions when build command is defined', async () => {
     await file.inTemporaryDirectory(async (tmpDir: string) => {
       // Given
       const bundlePath = joinPath(tmpDir, 'bundle.zip')
diff --git a/packages/app/src/cli/services/deploy/bundle.ts b/packages/app/src/cli/services/deploy/bundle.ts
index 5811ff368a9..c071d12e1b0 100644
--- a/packages/app/src/cli/services/deploy/bundle.ts
+++ b/packages/app/src/cli/services/deploy/bundle.ts
@@ -68,8 +68,16 @@ export async function bundleAndBuildExtensions(options: BundleOptions) {
     },
   }))
 
+  // Web builds must complete before extension builds start. Extensions like
+  // the admin module copy output from web builds (e.g. dist/) into the bundle
+  // via include_assets. Running them in parallel causes a race condition where
+  // dist/ is empty or missing when the admin extension tries to copy it.
+  if (webBuildProcesses.length > 0) {
+    await renderConcurrent({processes: webBuildProcesses, showTimestamps: false})
+  }
+
   await renderConcurrent({
-    processes: [webBuildProcesses, extensionBuildProcesses].flat(),
+    processes: extensionBuildProcesses,
     showTimestamps: false,
   })