diff --git a/components/admin/media-uploader.test.ts b/components/admin/media-uploader.test.ts
new file mode 100644
index 0000000..c8d7dc9
--- /dev/null
+++ b/components/admin/media-uploader.test.ts
@@ -0,0 +1,66 @@
+// @vitest-environment happy-dom
+import { act, createElement } from "react";
+import { createRoot, type Root } from "react-dom/client";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+const mocks = vi.hoisted(() => ({ error: vi.fn(), success: vi.fn() }));
+vi.mock("sonner", () => ({ toast: mocks }));
+import { MediaUploader } from "./media-uploader";
+
+let container: HTMLDivElement;
+let root: Root;
+const fetchUpload = vi.fn();
+const onReady = vi.fn();
+const onUploadingChange = vi.fn();
+
+beforeEach(async () => {
+  vi.clearAllMocks();
+  vi.stubGlobal("IS_REACT_ACT_ENVIRONMENT", true);
+  vi.stubGlobal("fetch", fetchUpload);
+  container = document.createElement("div");
+  document.body.append(container);
+  root = createRoot(container);
+  await act(async () => root.render(createElement(MediaUploader, { onReady, onUploadingChange })));
+});
+afterEach(async () => {
+  await act(async () => root.unmount());
+  container.remove();
+  vi.unstubAllGlobals();
+});
+
+async function selectImage() {
+  const input = container.querySelector("input")!;
+  Object.defineProperty(input, "files", { configurable: true, value: [new File(["image"], "test.png", { type: "image/png" })] });
+  await act(async () => input.dispatchEvent(new Event("change", { bubbles: true })));
+}
+
+describe("media upload responses", () => {
+  it("reports HTTP 503 when the network replaces the API error with HTML", async () => {
+    fetchUpload.mockResolvedValueOnce(new Response("<!doctype html><html>503 Service Unavailable</html>", {
+      status: 503, headers: { "Content-Type": "text/html" },
+    }));
+    await selectImage();
+    expect(mocks.error).toHaveBeenCalledWith(expect.stringContaining("HTTP 503"));
+    expect(onReady).not.toHaveBeenCalled();
+    expect(onUploadingChange.mock.calls).toEqual([[true], [false]]);
+    expect(container.querySelector("input")?.disabled).toBe(false);
+  });
+
+  it("preserves JSON API error details", async () => {
+    fetchUpload.mockResolvedValueOnce(Response.json({ error: "uploads-busy" }, { status: 429 }));
+    await selectImage();
+    expect(mocks.error).toHaveBeenCalledWith("uploads-busy");
+    expect(onReady).not.toHaveBeenCalled();
+    expect(container.querySelector("input")?.disabled).toBe(false);
+  });
+
+  it("passes a successful upload to the editor", async () => {
+    const media = { id: "media", url: "https://cdn.test/image.png", fileName: "test.png", width: 1, height: 1 };
+    fetchUpload.mockResolvedValueOnce(Response.json(media, { status: 201 }));
+    await selectImage();
+    expect(fetchUpload).toHaveBeenCalledWith("/api/admin/media", expect.objectContaining({ method: "POST", body: expect.any(FormData) }));
+    expect(onReady).toHaveBeenCalledExactlyOnceWith(media);
+    expect(mocks.success).toHaveBeenCalledTimes(1);
+    expect(onUploadingChange.mock.calls).toEqual([[true], [false]]);
+  });
+});
diff --git a/components/admin/media-uploader.tsx b/components/admin/media-uploader.tsx
index e82f31f..be31f54 100644
--- a/components/admin/media-uploader.tsx
+++ b/components/admin/media-uploader.tsx
@@ -49,8 +49,11 @@ export function MediaUploader({
         method: "POST",
         body,
       });
-      const result = await response.json() as UploadedMedia & { error?: string };
-      if (!response.ok) throw new Error(result.error || "upload");
+      if (!response.ok) {
+        const error = await response.json().catch(() => null) as { error?: string } | null;
+        throw new Error(error?.error || `อัปโหลดไม่สำเร็จ (HTTP ${response.status}) กรุณาลองอีกครั้ง`);
+      }
+      const result = await response.json() as UploadedMedia;
       onReady(result);
       toast.success("อัปโหลดรูปภาพแล้ว");
     } catch (cause) {