diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6a5f2b2..b45185e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,14 @@
 
 All notable changes to Multi-Debrid Downloader are documented in this file.
 
+## [2.0.28] - 2026-08-12
+
+### Startup reliability
+
+- Fixed Electron security registration so native WebContents and session APIs retain their required receiver during application startup.
+- Fixed packaged renderer IPC validation for case-insensitive Windows file paths.
+- Added explicit startup and renderer-load error logging for future launch diagnostics.
+
 ## [2.0.27] - 2026-08-12
 
 ### Startup reliability
diff --git a/package-lock.json b/package-lock.json
index 20f1fa4..f395226 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "real-debrid-downloader",
-  "version": "2.0.27",
+  "version": "2.0.28",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "real-debrid-downloader",
-      "version": "2.0.27",
+      "version": "2.0.28",
       "license": "MIT",
       "dependencies": {
         "adm-zip": "0.6.0",
diff --git a/package.json b/package.json
index 009cf84..2459a4a 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "real-debrid-downloader",
-  "version": "2.0.27",
+  "version": "2.0.28",
   "description": "Desktop downloader",
   "main": "build/main/main/main.js",
   "author": "Sucukdeluxe",
diff --git a/src/main/browser-security.ts b/src/main/browser-security.ts
index be7ac8a..d1257c8 100644
--- a/src/main/browser-security.ts
+++ b/src/main/browser-security.ts
@@ -126,19 +126,19 @@ export function applyRemoteLoginSecurity(window: SecurityWindow, options: Remote
 
 function applyCommonSecurity(window: SecurityWindow, externalHosts: readonly HttpsHostRule[]): void {
   const setWindowOpenHandler = window.webContents.setWindowOpenHandler as (handler: (details: { url: string }) => { action: "deny" }) => unknown;
-  setWindowOpenHandler((details) => {
+  setWindowOpenHandler.call(window.webContents, (details) => {
     void openAllowedExternalUrl(details.url, externalHosts);
     return { action: "deny" };
   });
   const setPermissionRequestHandler = window.webContents.session.setPermissionRequestHandler as (handler: (webContents: unknown, permission: string, callback: (allowed: boolean) => void) => void) => unknown;
-  setPermissionRequestHandler((_webContents, _permission, callback) => {
+  setPermissionRequestHandler.call(window.webContents.session, (_webContents, _permission, callback) => {
     callback(false);
   });
 }
 
 function onNavigation(window: SecurityWindow, event: "will-navigate" | "will-redirect", listener: (event: NavigationEvent, url: string) => void): void {
   const on = window.webContents.on as (event: "will-navigate" | "will-redirect", listener: (event: NavigationEvent, url: string) => void) => unknown;
-  on(event, listener);
+  on.call(window.webContents, event, listener);
 }
 
 function isExpectedRendererUrl(rawUrl: string, expectedUrl: string): boolean {
diff --git a/src/main/ipc-security.ts b/src/main/ipc-security.ts
index 998ca1c..defef03 100644
--- a/src/main/ipc-security.ts
+++ b/src/main/ipc-security.ts
@@ -40,7 +40,9 @@ function isPackagedRendererUrl(senderUrl: string, appPath: string): boolean {
     }
     const senderPath = path.resolve(fileURLToPath(parsed));
     const rendererPath = path.resolve(appPath, "build", "renderer");
-    return senderPath === rendererPath || senderPath.startsWith(rendererPath + path.sep);
+    const actualPath = process.platform === "win32" ? senderPath.toLowerCase() : senderPath;
+    const trustedRendererPath = process.platform === "win32" ? rendererPath.toLowerCase() : rendererPath;
+    return actualPath === trustedRendererPath || actualPath.startsWith(trustedRendererPath + path.sep);
   } catch {
     return false;
   }
diff --git a/src/main/main.ts b/src/main/main.ts
index fc3cac7..656db10 100644
--- a/src/main/main.ts
+++ b/src/main/main.ts
@@ -148,8 +148,8 @@ function armScheduledStart(schedMs: number, opts: { startOnPast: boolean }): voi
   logger.info(`Geplanter Start gearmt: ${new Date(schedMs).toLocaleString()}`);
 }
 
-function createWindow(): BrowserWindow {
-  const window = new BrowserWindow({
+function createWindow(): BrowserWindow {
+  const window = new BrowserWindow({
     width: 1920,
     height: 1080,
     minWidth: 1120,
@@ -160,6 +160,10 @@ function createWindow(): BrowserWindow {
     webPreferences: createMainWindowWebPreferences(path.join(__dirname, "../preload/preload.js"))
   });
 
+  window.webContents.on("did-fail-load", (_event, errorCode, errorDescription, validatedURL, isMainFrame) => {
+    logger.error(`Renderer-Laden fehlgeschlagen: id=${window.id} code=${errorCode} mainFrame=${isMainFrame} url=${validatedURL} error=${errorDescription}`);
+  });
+
   applyMainWindowSecurity(window, {
     rendererUrl: getTrustedRendererUrl(),
     externalHosts: MAIN_WINDOW_EXTERNAL_HOSTS
@@ -181,10 +185,14 @@ function createWindow(): BrowserWindow {
   window.setMenuBarVisibility(false);
   window.setAutoHideMenuBar(true);
 
-  if (isDevMode()) {
-    void window.loadURL(DEV_SERVER_URL);
-  } else {
-    void window.loadFile(path.join(app.getAppPath(), "build", "renderer", "index.html"));
+  if (isDevMode()) {
+    void window.loadURL(DEV_SERVER_URL).catch((error) => {
+      logger.error(`Renderer-Start fehlgeschlagen: ${String(error?.stack || error)}`);
+    });
+  } else {
+    void window.loadFile(path.join(app.getAppPath(), "build", "renderer", "index.html")).catch((error) => {
+      logger.error(`Renderer-Start fehlgeschlagen: ${String(error?.stack || error)}`);
+    });
   }
 
   return window;
@@ -955,19 +963,21 @@ app.whenReady().then(() => {
       bindMainWindowLifecycle(mainWindow);
     }
   });
-}).catch((error) => {
-  console.error("App startup failed:", error);
-  app.quit();
-});
-
-app.on("window-all-closed", () => {
-  if (process.platform !== "darwin") {
-    app.quit();
-  }
-});
-
-app.on("before-quit", () => {
-  if (updateQuitTimer) { clearTimeout(updateQuitTimer); updateQuitTimer = null; }
+}).catch((error) => {
+  logger.error(`App-Start fehlgeschlagen: ${String(error?.stack || error)}`);
+  console.error("App startup failed:", error);
+  app.quit();
+});
+
+app.on("window-all-closed", () => {
+  logger.warn("Alle Hauptfenster geschlossen");
+  if (process.platform !== "darwin") {
+    app.quit();
+  }
+});
+
+app.on("before-quit", () => {
+  if (updateQuitTimer) { clearTimeout(updateQuitTimer); updateQuitTimer = null; }
   stopClipboardWatcher();
   destroyTray();
   shutdownDaemon();
diff --git a/tests/browser-security.test.ts b/tests/browser-security.test.ts
index b3637c8..c14cfa5 100644
--- a/tests/browser-security.test.ts
+++ b/tests/browser-security.test.ts
@@ -96,6 +96,37 @@ describe("browser-security", () => {
     });
   });
 
+  it("keeps native WebContents receivers when registering main-window security", () => {
+    const listeners = new Map<string, NavigationHandler>();
+    const webContents = {
+      on(this: unknown, event: string, listener: NavigationHandler) {
+        if (this !== webContents) {
+          throw new TypeError("WebContents receiver missing");
+        }
+        listeners.set(event, listener);
+      },
+      setWindowOpenHandler(this: unknown, _handler: WindowOpenHandler) {
+        if (this !== webContents) {
+          throw new TypeError("WebContents receiver missing");
+        }
+      },
+      session: {
+        setPermissionRequestHandler(this: unknown, _handler: PermissionHandler) {
+          if (this !== webContents.session) {
+            throw new TypeError("Session receiver missing");
+          }
+        }
+      }
+    };
+
+    expect(() => applyMainWindowSecurity({ webContents }, {
+      rendererUrl: "http://localhost:5180",
+      externalHosts: githubOnly
+    })).not.toThrow();
+    expect(listeners.has("will-navigate")).toBe(true);
+    expect(listeners.has("will-redirect")).toBe(true);
+  });
+
   it("denies main-window navigation to an untrusted origin", () => {
     const harness = createWindow();
     applyMainWindowSecurity(harness.window, {
diff --git a/tests/ipc-security.test.ts b/tests/ipc-security.test.ts
index d47e800..e7a2ced 100644
--- a/tests/ipc-security.test.ts
+++ b/tests/ipc-security.test.ts
@@ -40,6 +40,25 @@ describe("ipc-security", () => {
     })).not.toThrow();
   });
 
+  it("accepts packaged renderer IPC despite Windows path casing differences", () => {
+    const platform = Object.getOwnPropertyDescriptor(process, "platform");
+    Object.defineProperty(process, "platform", { configurable: true, value: "win32" });
+    try {
+      const appPath = path.join("C:", "Program Files", "MDD", "resources", "app.asar");
+      const rendererUrl = "file:///c:/program%20files/mdd/resources/app.asar/build/renderer/index.html";
+
+      expect(() => assertTrustedIpcSender(eventFor(rendererUrl), {
+        isPackaged: true,
+        devServerUrl: "http://localhost:5180",
+        appPath
+      })).not.toThrow();
+    } finally {
+      if (platform) {
+        Object.defineProperty(process, "platform", platform);
+      }
+    }
+  });
+
   it("rejects IPC from local files outside the packaged renderer tree", () => {
     const appPath = path.join("C:", "Program Files", "MDD", "resources", "app.asar");
     const attackerUrl = pathToFileURL(path.join("C:", "Users", "Public", "attacker.html")).toString();