diff --git a/apps/desktop/src/i18n/strings/en_EN.json b/apps/desktop/src/i18n/strings/en_EN.json
index fdcdf662d1..c4e0bad993 100644
--- a/apps/desktop/src/i18n/strings/en_EN.json
+++ b/apps/desktop/src/i18n/strings/en_EN.json
@@ -27,6 +27,10 @@
         "yes": "Yes"
     },
     "confirm_quit": "Are you sure you want to quit?",
+    "download": {
+        "unable_to_open_description": "The file could not be opened. It may have been moved or deleted.",
+        "unable_to_open_title": "Unable to open file"
+    },
     "edit_menu": {
         "speech": "Speech",
         "speech_start_speaking": "Start Speaking",
diff --git a/apps/desktop/src/webcontents-handler.test.ts b/apps/desktop/src/webcontents-handler.test.ts
new file mode 100644
index 0000000000..b2cc105afa
--- /dev/null
+++ b/apps/desktop/src/webcontents-handler.test.ts
@@ -0,0 +1,125 @@
+/*
+Copyright 2026 hayaksi1
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { beforeEach, describe, expect, it, vi, type Mock } from "vitest";
+import { dialog, shell, type WebContents } from "electron";
+
+// The `userDownloadAction` listener is registered at import time, so capture the callbacks that
+// `ipcMain.on` receives in order to invoke the handler under test directly.
+const { ipcHandlers } = vi.hoisted(() => ({
+    ipcHandlers: {} as Record<string, (...args: unknown[]) => unknown>,
+}));
+
+vi.mock("electron", () => ({
+    clipboard: {},
+    Menu: class {},
+    MenuItem: class {},
+    shell: { openExternal: vi.fn(), openPath: vi.fn() },
+    dialog: { showMessageBox: vi.fn(), showSaveDialog: vi.fn() },
+    ipcMain: {
+        on: vi.fn((channel: string, cb: (...args: unknown[]) => unknown) => {
+            ipcHandlers[channel] = cb;
+        }),
+    },
+}));
+vi.mock("./language-helper.js", () => ({ _t: (key: string): string => key }));
+vi.mock("./config.js", () => ({ getConfig: (): Record<string, never> => ({}) }));
+vi.mock("./save-image.js", () => ({ saveImageToFile: vi.fn() }));
+
+const registerWebContentsHandlers = (await import("./webcontents-handler.js")).default;
+
+interface MockWebContents {
+    setWindowOpenHandler: Mock;
+    on: Mock;
+    send: Mock;
+    session: { on: Mock };
+    sessionHandlers: Record<string, (...args: unknown[]) => void>;
+}
+
+function makeWebContents(): MockWebContents {
+    const sessionHandlers: Record<string, (...args: unknown[]) => void> = {};
+    return {
+        setWindowOpenHandler: vi.fn(),
+        on: vi.fn(),
+        send: vi.fn(),
+        session: {
+            on: vi.fn((ev: string, cb: (...args: unknown[]) => void): void => {
+                sessionHandlers[ev] = cb;
+            }),
+        },
+        sessionHandlers,
+    };
+}
+
+/**
+ * Drives the real will-download → done("completed") flow so the download is registered the way it is
+ * in production, and returns the id the handler assigned to it.
+ */
+function completeDownload(wc: MockWebContents, savePath: string): number {
+    const doneHandlers: Record<string, (...args: unknown[]) => void> = {};
+    const item = {
+        once: (ev: string, cb: (...args: unknown[]) => void): void => {
+            doneHandlers[ev] = cb;
+        },
+        getSavePath: (): string => savePath,
+    };
+    wc.sessionHandlers["will-download"]({}, item);
+    doneHandlers["done"]({}, "completed");
+    const completed = wc.send.mock.calls.find((c) => c[0] === "userDownloadCompleted");
+    return (completed![1] as { id: number }).id;
+}
+
+describe("userDownloadAction handler", () => {
+    let wc: MockWebContents;
+
+    beforeEach(() => {
+        vi.clearAllMocks();
+        wc = makeWebContents();
+        registerWebContentsHandlers(wc as unknown as WebContents);
+    });
+
+    it("opens the file when the user clicks Open on a known download", async () => {
+        vi.mocked(shell.openPath).mockResolvedValue("");
+        const id = completeDownload(wc, "/tmp/file.pdf");
+
+        await ipcHandlers["userDownloadAction"]({}, { id, open: true });
+
+        expect(shell.openPath).toHaveBeenCalledWith("/tmp/file.pdf");
+        expect(dialog.showMessageBox).not.toHaveBeenCalled();
+    });
+
+    it("shows the underlying error when the open fails, rather than failing silently", async () => {
+        vi.mocked(shell.openPath).mockResolvedValue("LSOpenURLsWithRole failed");
+        const id = completeDownload(wc, "/tmp/file.pdf");
+
+        await ipcHandlers["userDownloadAction"]({}, { id, open: true });
+
+        expect(shell.openPath).toHaveBeenCalledWith("/tmp/file.pdf");
+        expect(dialog.showMessageBox).toHaveBeenCalledWith(
+            expect.objectContaining({ type: "error", detail: "LSOpenURLsWithRole failed" }),
+        );
+    });
+
+    it("does not open anything on a plain dismiss", async () => {
+        const id = completeDownload(wc, "/tmp/file.pdf");
+
+        await ipcHandlers["userDownloadAction"]({}, { id, open: false });
+
+        expect(shell.openPath).not.toHaveBeenCalled();
+    });
+
+    it("removes the entry so a repeated open is a no-op", async () => {
+        vi.mocked(shell.openPath).mockResolvedValue("");
+        const id = completeDownload(wc, "/tmp/file.pdf");
+
+        await ipcHandlers["userDownloadAction"]({}, { id, open: true });
+        vi.mocked(shell.openPath).mockClear();
+        await ipcHandlers["userDownloadAction"]({}, { id, open: true });
+
+        expect(shell.openPath).not.toHaveBeenCalled();
+    });
+});
diff --git a/apps/desktop/src/webcontents-handler.ts b/apps/desktop/src/webcontents-handler.ts
index 3dc3d26ca0..4e473f9929 100644
--- a/apps/desktop/src/webcontents-handler.ts
+++ b/apps/desktop/src/webcontents-handler.ts
@@ -243,12 +243,22 @@ function onEditableContextMenu(ev: Event, params: ContextMenuParams, webContents
 
 let userDownloadIndex = 0;
 const userDownloadMap = new Map<number, string>(); // Map from id to path
-ipcMain.on("userDownloadAction", function (ev: IpcMainEvent, { id, open = false }) {
+ipcMain.on("userDownloadAction", async function (ev: IpcMainEvent, { id, open = false }) {
     const path = userDownloadMap.get(id);
-    if (open && path) {
-        void shell.openPath(path);
-    }
     userDownloadMap.delete(id);
+    if (open && path) {
+        // openPath resolves to a non-empty error string on failure, an empty one on success.
+        const error = await shell.openPath(path);
+        if (error) {
+            console.error(`Failed to open downloaded file ${path}: ${error}`);
+            void dialog.showMessageBox({
+                type: "error",
+                title: _t("download|unable_to_open_title"),
+                message: _t("download|unable_to_open_description"),
+                detail: error,
+            });
+        }
+    }
 });
 
 export default (webContents: WebContents): void => {