diff --git a/packages/storefront/src/images/use-ssr-picture.ts b/packages/storefront/src/images/use-ssr-picture.ts
index 5aebe6dfc..fe207e475 100644
--- a/packages/storefront/src/images/use-ssr-picture.ts
+++ b/packages/storefront/src/images/use-ssr-picture.ts
@@ -209,16 +209,27 @@ const useSSRPicture = async (params: UsePictureParams) => {
     sizes = `${(widths[0] / 2)}px`;
   }
 
-  const { image, sources } = await getPicture({
-    src,
-    widths,
-    formats,
-    aspectRatio,
-    fit,
-    background,
-    position,
-    alt,
-  });
+  let image: GetPictureResult['image'];
+  let sources: GetPictureResult['sources'];
+  if (aspectRatio) {
+    ({ image, sources } = await getPicture({
+      src,
+      widths,
+      formats,
+      aspectRatio,
+      fit,
+      background,
+      position,
+      alt,
+    }));
+  } else {
+    // Unknown image size, e.g. a new CMS upload not deployed yet (CMS preview).
+    // `getPicture` would throw in the middle of the SSR stream and hang the response,
+    // so render the original file instead
+    console.warn(`Could not get size of image ${src}, rendering original file`);
+    image = { src };
+    sources = [];
+  }
   delete image.width;
   delete image.height;
   if (import.meta.env.PROD && assetsPrefix && image.src?.charAt(0) === '/') {
diff --git a/packages/storefront/src/lib/components/Picture.astro b/packages/storefront/src/lib/components/Picture.astro
index 9543bcc82..c4967c4e0 100644
--- a/packages/storefront/src/lib/components/Picture.astro
+++ b/packages/storefront/src/lib/components/Picture.astro
@@ -83,8 +83,11 @@ const {
   }),
   assetsPrefix: Astro.locals.assetsPrefix,
 });
-if (imgAttrs?.src) {
-  imgAttrs.src += versionSuffix;
+if (imgAttrs?.src && versionSuffix) {
+  // Original file fallback (unknown image size) has no query string yet
+  imgAttrs.src += imgAttrs.src.includes('?')
+    ? versionSuffix
+    : versionSuffix.replace('&', '?');
 }
 ---
 
diff --git a/packages/storefront/tests/ssr-picture.test.ts b/packages/storefront/tests/ssr-picture.test.ts
new file mode 100644
index 000000000..0157f1bba
--- /dev/null
+++ b/packages/storefront/tests/ssr-picture.test.ts
@@ -0,0 +1,59 @@
+import {
+  describe,
+  test,
+  expect,
+  vi,
+  afterEach,
+} from 'vitest';
+import { useSSRPicture } from '~/images/use-ssr-picture';
+
+const builtPicture = {
+  image: { src: '/_astro/banner_abc.jpg', width: 1024, height: 576 },
+  sources: [
+    { type: 'image/avif', srcset: '/_astro/banner_abc.avif 640w,/_astro/banner_def.avif 1024w' },
+    { type: 'image/webp', srcset: '/_astro/banner_abc.webp 640w,/_astro/banner_def.webp 1024w' },
+  ],
+};
+
+describe('SSR <picture> attributes', () => {
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  test('renders the original file when the image size is unknown', async () => {
+    // e.g. a new upload on CMS preview, not listed on the deployed images manifest
+    const warn = vi.spyOn(console, 'warn').mockImplementation(() => {});
+    const getPicture = vi.fn(async () => {
+      throw new Error('`aspectRatio` must be provided for remote images');
+    });
+    const { sources, imgAttrs } = await useSSRPicture({
+      src: '/img/uploads/new-banner.jpg',
+      alt: 'New banner',
+      widths: [640, 1024],
+      tryImageSize: async () => ({}),
+      getPicture,
+    });
+    expect(getPicture).not.toHaveBeenCalled();
+    expect(warn).toHaveBeenCalledWith(expect.stringContaining('/img/uploads/new-banner.jpg'));
+    expect(sources).toEqual([]);
+    expect(imgAttrs?.src).toBe('/img/uploads/new-banner.jpg');
+    expect(imgAttrs?.alt).toBe('New banner');
+  });
+
+  test('keeps optimized sources when the image size is known', async () => {
+    const getPicture = vi.fn(async () => structuredClone(builtPicture));
+    const { sources, imgAttrs } = await useSSRPicture({
+      src: '/img/uploads/banner.jpg',
+      alt: 'Banner',
+      widths: [640, 1024],
+      tryImageSize: async () => ({ width: 1600, height: 900 }),
+      getPicture,
+    });
+    expect(getPicture).toHaveBeenCalledWith(expect.objectContaining({
+      src: '/img/uploads/banner.jpg',
+      aspectRatio: 1600 / 900,
+    }));
+    expect(sources).toEqual(builtPicture.sources);
+    expect(imgAttrs?.src).toBeNull();
+  });
+});