diff --git a/typescript-version/package-lock.json b/typescript-version/package-lock.json
index 415d946..fd0ad1a 100644
--- a/typescript-version/package-lock.json
+++ b/typescript-version/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "twitch-vod-manager",
-  "version": "3.8.8",
+  "version": "3.9.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "twitch-vod-manager",
-      "version": "3.8.8",
+      "version": "3.9.0",
       "license": "MIT",
       "dependencies": {
         "axios": "^1.6.0",
diff --git a/typescript-version/package.json b/typescript-version/package.json
index f94e106..2c794a2 100644
--- a/typescript-version/package.json
+++ b/typescript-version/package.json
@@ -1,6 +1,6 @@
 {
   "name": "twitch-vod-manager",
-  "version": "3.8.8",
+  "version": "3.9.0",
   "description": "Twitch VOD Manager - Download Twitch VODs easily",
   "main": "dist/main.js",
   "author": "xRangerDE",
diff --git a/typescript-version/src/index.html b/typescript-version/src/index.html
index 305d937..ba2109b 100644
--- a/typescript-version/src/index.html
+++ b/typescript-version/src/index.html
@@ -130,6 +130,7 @@
                 <div class="queue-list" id="queueList"></div>
                 <div class="queue-actions">
                     <button class="btn btn-start" id="btnStart" onclick="toggleDownload()">Start</button>
+                    <button class="btn btn-retry" id="btnRetryFailed" onclick="retryFailedDownloads()">Fehler neu</button>
                     <button class="btn btn-clear" id="btnClear" onclick="clearCompleted()">Leeren</button>
                 </div>
             </div>
@@ -343,9 +344,30 @@
 
                     <div class="settings-card">
                         <h3 id="updateTitle">Updates</h3>
-                        <p id="versionInfo" style="margin-bottom: 10px; color: var(--text-secondary);">Version: v3.8.8</p>
+                        <p id="versionInfo" style="margin-bottom: 10px; color: var(--text-secondary);">Version: v3.9.0</p>
                         <button class="btn-secondary" id="checkUpdateBtn" onclick="checkUpdate()">Nach Updates suchen</button>
                     </div>
+
+                    <div class="settings-card">
+                        <h3 id="preflightTitle">System-Check</h3>
+                        <div class="form-row" style="margin-bottom: 10px;">
+                            <button class="btn-secondary" id="btnPreflightRun" onclick="runPreflight(false)">Check ausfuhren</button>
+                            <button class="btn-secondary" id="btnPreflightFix" onclick="runPreflight(true)">Auto-Fix Tools</button>
+                        </div>
+                        <pre id="preflightResult" class="log-panel">Noch kein Check ausgefuhrt.</pre>
+                    </div>
+
+                    <div class="settings-card">
+                        <h3 id="debugLogTitle">Live Debug-Log</h3>
+                        <div class="form-row" style="margin-bottom: 10px; align-items: center;">
+                            <button class="btn-secondary" id="btnRefreshLog" onclick="refreshDebugLog()">Aktualisieren</button>
+                            <label style="display:flex; align-items:center; gap:6px; font-size:13px; color: var(--text-secondary);">
+                                <input type="checkbox" id="debugAutoRefresh" onchange="toggleDebugAutoRefresh(this.checked)">
+                                <span id="autoRefreshText">Auto-Refresh</span>
+                            </label>
+                        </div>
+                        <pre id="debugLogOutput" class="log-panel">Lade...</pre>
+                    </div>
                 </div>
             </div>
 
@@ -354,7 +376,7 @@
                     <div class="status-dot" id="statusDot"></div>
                     <span id="statusText">Nicht verbunden</span>
                 </div>
-                <span id="versionText">v3.8.8</span>
+                <span id="versionText">v3.9.0</span>
             </div>
         </main>
     </div>
diff --git a/typescript-version/src/main.ts b/typescript-version/src/main.ts
index b85981c..af33d90 100644
--- a/typescript-version/src/main.ts
+++ b/typescript-version/src/main.ts
@@ -8,7 +8,7 @@ import { autoUpdater } from 'electron-updater';
 // ==========================================
 // CONFIG & CONSTANTS
 // ==========================================
-const APP_VERSION = '3.8.8';
+const APP_VERSION = '3.9.0';
 const UPDATE_CHECK_URL = 'http://24-music.de/version.json';
 
 // Paths
@@ -88,6 +88,22 @@ interface DownloadResult {
     error?: string;
 }
 
+interface PreflightChecks {
+    internet: boolean;
+    streamlink: boolean;
+    ffmpeg: boolean;
+    ffprobe: boolean;
+    downloadPathWritable: boolean;
+}
+
+interface PreflightResult {
+    ok: boolean;
+    autoFixApplied: boolean;
+    checks: PreflightChecks;
+    messages: string[];
+    timestamp: string;
+}
+
 interface DownloadProgress {
     id: string;
     progress: number;
@@ -214,6 +230,94 @@ function getStreamlinkPath(): string {
     return 'streamlink';
 }
 
+function sleep(ms: number): Promise<void> {
+    return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
+function isDownloadPathWritable(targetPath: string): boolean {
+    try {
+        fs.mkdirSync(targetPath, { recursive: true });
+        const probeFile = path.join(targetPath, `.write_test_${Date.now()}.tmp`);
+        fs.writeFileSync(probeFile, 'ok');
+        fs.unlinkSync(probeFile);
+        return true;
+    } catch {
+        return false;
+    }
+}
+
+async function hasInternetConnection(): Promise<boolean> {
+    try {
+        const res = await axios.get('https://id.twitch.tv/oauth2/validate', {
+            timeout: 5000,
+            validateStatus: () => true
+        });
+        return res.status > 0;
+    } catch {
+        return false;
+    }
+}
+
+async function runPreflight(autoFix = false): Promise<PreflightResult> {
+    appendDebugLog('preflight-start', { autoFix });
+
+    refreshBundledToolPaths();
+
+    const checks: PreflightChecks = {
+        internet: await hasInternetConnection(),
+        streamlink: false,
+        ffmpeg: false,
+        ffprobe: false,
+        downloadPathWritable: isDownloadPathWritable(config.download_path)
+    };
+
+    if (autoFix) {
+        await ensureStreamlinkInstalled();
+        await ensureFfmpegInstalled();
+        refreshBundledToolPaths();
+    }
+
+    const streamlinkCmd = getStreamlinkCommand();
+    checks.streamlink = canExecuteCommand(streamlinkCmd.command, [...streamlinkCmd.prefixArgs, '--version']);
+
+    const ffmpegPath = getFFmpegPath();
+    const ffprobePath = getFFprobePath();
+    checks.ffmpeg = canExecuteCommand(ffmpegPath, ['-version']);
+    checks.ffprobe = canExecuteCommand(ffprobePath, ['-version']);
+
+    const messages: string[] = [];
+    if (!checks.internet) messages.push('Keine Internetverbindung erkannt.');
+    if (!checks.streamlink) messages.push('Streamlink fehlt oder ist nicht startbar.');
+    if (!checks.ffmpeg) messages.push('FFmpeg fehlt oder ist nicht startbar.');
+    if (!checks.ffprobe) messages.push('FFprobe fehlt oder ist nicht startbar.');
+    if (!checks.downloadPathWritable) messages.push('Download-Ordner ist nicht beschreibbar.');
+
+    const result: PreflightResult = {
+        ok: messages.length === 0,
+        autoFixApplied: autoFix,
+        checks,
+        messages,
+        timestamp: new Date().toISOString()
+    };
+
+    appendDebugLog('preflight-finished', result);
+    return result;
+}
+
+function readDebugLog(lines = 200): string {
+    try {
+        if (!fs.existsSync(DEBUG_LOG_FILE)) {
+            return 'Debug-Log ist leer.';
+        }
+
+        const text = fs.readFileSync(DEBUG_LOG_FILE, 'utf-8');
+        const rows = text.split(/\r?\n/).filter(Boolean);
+        return rows.slice(-lines).join('\n') || 'Debug-Log ist leer.';
+    } catch (e) {
+        return `Debug-Log konnte nicht gelesen werden: ${String(e)}`;
+    }
+}
+
 function canExecute(cmd: string): boolean {
     try {
         execSync(cmd, { stdio: 'ignore', windowsHide: true });
@@ -1352,13 +1456,47 @@ async function processQueue(): Promise<void> {
 
         item.last_error = '';
 
-        const result = await downloadVOD(item, (progress) => {
-            mainWindow?.webContents.send('download-progress', progress);
-        });
+        let finalResult: DownloadResult = { success: false, error: 'Unbekannter Fehler beim Download' };
 
-        item.status = result.success ? 'completed' : 'error';
-        item.progress = result.success ? 100 : 0;
-        item.last_error = result.success ? '' : (result.error || 'Unbekannter Fehler beim Download');
+        for (let attempt = 1; attempt <= MAX_RETRY_ATTEMPTS; attempt++) {
+            appendDebugLog('queue-item-attempt', { itemId: item.id, attempt, max: MAX_RETRY_ATTEMPTS });
+
+            const result = await downloadVOD(item, (progress) => {
+                mainWindow?.webContents.send('download-progress', progress);
+            });
+
+            if (result.success) {
+                finalResult = result;
+                break;
+            }
+
+            finalResult = result;
+
+            if (!isDownloading || currentDownloadCancelled) {
+                finalResult = { success: false, error: 'Download wurde abgebrochen.' };
+                break;
+            }
+
+            if (attempt < MAX_RETRY_ATTEMPTS) {
+                item.last_error = `Versuch ${attempt}/${MAX_RETRY_ATTEMPTS} fehlgeschlagen: ${result.error || 'Unbekannter Fehler'}`;
+                mainWindow?.webContents.send('download-progress', {
+                    id: item.id,
+                    progress: -1,
+                    speed: '',
+                    eta: '',
+                    status: `Neuer Versuch in ${RETRY_DELAY_SECONDS}s...`,
+                    currentPart: item.currentPart,
+                    totalParts: item.totalParts
+                } as DownloadProgress);
+                saveQueue(downloadQueue);
+                mainWindow?.webContents.send('queue-updated', downloadQueue);
+                await sleep(RETRY_DELAY_SECONDS * 1000);
+            }
+        }
+
+        item.status = finalResult.success ? 'completed' : 'error';
+        item.progress = finalResult.success ? 100 : 0;
+        item.last_error = finalResult.success ? '' : (finalResult.error || 'Unbekannter Fehler beim Download');
         appendDebugLog('queue-item-finished', {
             itemId: item.id,
             status: item.status,
@@ -1521,6 +1659,28 @@ ipcMain.handle('clear-completed', () => {
     return downloadQueue;
 });
 
+ipcMain.handle('retry-failed-downloads', () => {
+    downloadQueue = downloadQueue.map((item) => {
+        if (item.status !== 'error') return item;
+
+        return {
+            ...item,
+            status: 'pending',
+            progress: 0,
+            last_error: ''
+        };
+    });
+
+    saveQueue(downloadQueue);
+    mainWindow?.webContents.send('queue-updated', downloadQueue);
+
+    if (!isDownloading) {
+        void processQueue();
+    }
+
+    return downloadQueue;
+});
+
 ipcMain.handle('start-download', async () => {
     const hasPendingItems = downloadQueue.some(item => item.status !== 'completed');
     if (!hasPendingItems) {
@@ -1636,6 +1796,14 @@ ipcMain.handle('download-clip', async (_, clipUrl: string) => {
     });
 });
 
+ipcMain.handle('run-preflight', async (_, autoFix: boolean = false) => {
+    return await runPreflight(autoFix);
+});
+
+ipcMain.handle('get-debug-log', async (_, lines: number = 200) => {
+    return readDebugLog(lines);
+});
+
 ipcMain.handle('is-downloading', () => isDownloading);
 
 // Video Cutter IPC
diff --git a/typescript-version/src/preload.ts b/typescript-version/src/preload.ts
index e2577aa..0d803c6 100644
--- a/typescript-version/src/preload.ts
+++ b/typescript-version/src/preload.ts
@@ -61,6 +61,7 @@ contextBridge.exposeInMainWorld('api', {
     addToQueue: (item: Omit<QueueItem, 'id' | 'status' | 'progress'>) => ipcRenderer.invoke('add-to-queue', item),
     removeFromQueue: (id: string) => ipcRenderer.invoke('remove-from-queue', id),
     clearCompleted: () => ipcRenderer.invoke('clear-completed'),
+    retryFailedDownloads: () => ipcRenderer.invoke('retry-failed-downloads'),
 
     // Download
     startDownload: () => ipcRenderer.invoke('start-download'),
@@ -91,6 +92,8 @@ contextBridge.exposeInMainWorld('api', {
     downloadUpdate: () => ipcRenderer.invoke('download-update'),
     installUpdate: () => ipcRenderer.invoke('install-update'),
     openExternal: (url: string) => ipcRenderer.invoke('open-external', url),
+    runPreflight: (autoFix: boolean) => ipcRenderer.invoke('run-preflight', autoFix),
+    getDebugLog: (lines: number) => ipcRenderer.invoke('get-debug-log', lines),
 
     // Events
     onDownloadProgress: (callback: (progress: DownloadProgress) => void) => {
diff --git a/typescript-version/src/renderer-globals.d.ts b/typescript-version/src/renderer-globals.d.ts
index 9d7996d..7de094b 100644
--- a/typescript-version/src/renderer-globals.d.ts
+++ b/typescript-version/src/renderer-globals.d.ts
@@ -87,6 +87,22 @@ interface UpdateDownloadProgress {
     total: number;
 }
 
+interface PreflightChecks {
+    internet: boolean;
+    streamlink: boolean;
+    ffmpeg: boolean;
+    ffprobe: boolean;
+    downloadPathWritable: boolean;
+}
+
+interface PreflightResult {
+    ok: boolean;
+    autoFixApplied: boolean;
+    checks: PreflightChecks;
+    messages: string[];
+    timestamp: string;
+}
+
 interface ApiBridge {
     getConfig(): Promise<AppConfig>;
     saveConfig(config: Partial<AppConfig>): Promise<AppConfig>;
@@ -97,6 +113,7 @@ interface ApiBridge {
     addToQueue(item: Omit<QueueItem, 'id' | 'status' | 'progress'>): Promise<QueueItem[]>;
     removeFromQueue(id: string): Promise<QueueItem[]>;
     clearCompleted(): Promise<QueueItem[]>;
+    retryFailedDownloads(): Promise<QueueItem[]>;
     startDownload(): Promise<boolean>;
     cancelDownload(): Promise<boolean>;
     isDownloading(): Promise<boolean>;
@@ -115,6 +132,8 @@ interface ApiBridge {
     downloadUpdate(): Promise<{ downloading?: boolean; error?: boolean }>;
     installUpdate(): Promise<void>;
     openExternal(url: string): Promise<void>;
+    runPreflight(autoFix: boolean): Promise<PreflightResult>;
+    getDebugLog(lines: number): Promise<string>;
     onDownloadProgress(callback: (progress: DownloadProgress) => void): void;
     onQueueUpdated(callback: (queue: QueueItem[]) => void): void;
     onDownloadStarted(callback: () => void): void;
diff --git a/typescript-version/src/renderer-locale-de.ts b/typescript-version/src/renderer-locale-de.ts
index 51eed3c..114619b 100644
--- a/typescript-version/src/renderer-locale-de.ts
+++ b/typescript-version/src/renderer-locale-de.ts
@@ -7,6 +7,7 @@ const UI_TEXT_DE = {
         navMerge: 'Videos zusammenfugen',
         navSettings: 'Einstellungen',
         queueTitle: 'Warteschlange',
+        retryFailed: 'Fehler neu',
         clearQueue: 'Leeren',
         refresh: 'Aktualisieren',
         streamerPlaceholder: 'Streamer hinzufugen...',
@@ -36,6 +37,13 @@ const UI_TEXT_DE = {
         partMinutesLabel: 'Teil-Lange (Minuten)',
         updateTitle: 'Updates',
         checkUpdates: 'Nach Updates suchen',
+        preflightTitle: 'System-Check',
+        preflightRun: 'Check ausfuhren',
+        preflightFix: 'Auto-Fix Tools',
+        preflightEmpty: 'Noch kein Check ausgefuhrt.',
+        debugLogTitle: 'Live Debug-Log',
+        refreshLog: 'Aktualisieren',
+        autoRefresh: 'Auto-Refresh',
         notConnected: 'Nicht verbunden'
     },
     status: {
diff --git a/typescript-version/src/renderer-locale-en.ts b/typescript-version/src/renderer-locale-en.ts
index 875dda3..79ef216 100644
--- a/typescript-version/src/renderer-locale-en.ts
+++ b/typescript-version/src/renderer-locale-en.ts
@@ -7,6 +7,7 @@ const UI_TEXT_EN = {
         navMerge: 'Merge Videos',
         navSettings: 'Settings',
         queueTitle: 'Queue',
+        retryFailed: 'Retry failed',
         clearQueue: 'Clear',
         refresh: 'Refresh',
         streamerPlaceholder: 'Add streamer...',
@@ -36,6 +37,13 @@ const UI_TEXT_EN = {
         partMinutesLabel: 'Part Length (Minutes)',
         updateTitle: 'Updates',
         checkUpdates: 'Check for updates',
+        preflightTitle: 'System Check',
+        preflightRun: 'Run check',
+        preflightFix: 'Auto-fix tools',
+        preflightEmpty: 'No checks run yet.',
+        debugLogTitle: 'Live Debug Log',
+        refreshLog: 'Refresh',
+        autoRefresh: 'Auto refresh',
         notConnected: 'Not connected'
     },
     status: {
diff --git a/typescript-version/src/renderer-queue.ts b/typescript-version/src/renderer-queue.ts
index dc936b4..d17f45b 100644
--- a/typescript-version/src/renderer-queue.ts
+++ b/typescript-version/src/renderer-queue.ts
@@ -19,6 +19,11 @@ async function clearCompleted(): Promise<void> {
     renderQueue();
 }
 
+async function retryFailedDownloads(): Promise<void> {
+    queue = await window.api.retryFailedDownloads();
+    renderQueue();
+}
+
 function getQueueStatusLabel(item: QueueItem): string {
     if (item.status === 'completed') return UI_TEXT.queue.statusDone;
     if (item.status === 'error') return UI_TEXT.queue.statusFailed;
diff --git a/typescript-version/src/renderer-settings.ts b/typescript-version/src/renderer-settings.ts
index 04592ae..cf5d2be 100644
--- a/typescript-version/src/renderer-settings.ts
+++ b/typescript-version/src/renderer-settings.ts
@@ -40,6 +40,56 @@ function changeLanguage(lang: string): void {
     }
 }
 
+function renderPreflightResult(result: PreflightResult): void {
+    const entries = [
+        ['Internet', result.checks.internet],
+        ['Streamlink', result.checks.streamlink],
+        ['FFmpeg', result.checks.ffmpeg],
+        ['FFprobe', result.checks.ffprobe],
+        ['Download-Pfad', result.checks.downloadPathWritable]
+    ];
+
+    const lines = entries.map(([name, ok]) => `${ok ? 'OK' : 'FAIL'} ${name}`).join('\n');
+    const extra = result.messages.length ? `\n\n${result.messages.join('\n')}` : '\n\nAlles bereit.';
+
+    byId('preflightResult').textContent = `${lines}${extra}`;
+}
+
+async function runPreflight(autoFix = false): Promise<void> {
+    const btn = byId<HTMLButtonElement>(autoFix ? 'btnPreflightFix' : 'btnPreflightRun');
+    const old = btn.textContent || '';
+    btn.disabled = true;
+    btn.textContent = autoFix ? 'Fixe...' : 'Prufe...';
+
+    try {
+        const result = await window.api.runPreflight(autoFix);
+        renderPreflightResult(result);
+    } finally {
+        btn.disabled = false;
+        btn.textContent = old;
+    }
+}
+
+async function refreshDebugLog(): Promise<void> {
+    const text = await window.api.getDebugLog(250);
+    const panel = byId('debugLogOutput');
+    panel.textContent = text;
+    panel.scrollTop = panel.scrollHeight;
+}
+
+function toggleDebugAutoRefresh(enabled: boolean): void {
+    if (debugLogAutoRefreshTimer) {
+        clearInterval(debugLogAutoRefreshTimer);
+        debugLogAutoRefreshTimer = null;
+    }
+
+    if (enabled) {
+        debugLogAutoRefreshTimer = window.setInterval(() => {
+            void refreshDebugLog();
+        }, 1500);
+    }
+}
+
 async function saveSettings(): Promise<void> {
     const clientId = byId<HTMLInputElement>('clientId').value.trim();
     const clientSecret = byId<HTMLInputElement>('clientSecret').value.trim();
diff --git a/typescript-version/src/renderer-shared.ts b/typescript-version/src/renderer-shared.ts
index 36e8eac..9493b5b 100644
--- a/typescript-version/src/renderer-shared.ts
+++ b/typescript-version/src/renderer-shared.ts
@@ -38,3 +38,4 @@ let clipDialogData: ClipDialogData | null = null;
 let clipTotalSeconds = 0;
 
 let updateReady = false;
+let debugLogAutoRefreshTimer: number | null = null;
diff --git a/typescript-version/src/renderer-texts.ts b/typescript-version/src/renderer-texts.ts
index 560b202..e861b08 100644
--- a/typescript-version/src/renderer-texts.ts
+++ b/typescript-version/src/renderer-texts.ts
@@ -46,6 +46,7 @@ function applyLanguageToStaticUI(): void {
     setText('navMergeText', UI_TEXT.static.navMerge);
     setText('navSettingsText', UI_TEXT.static.navSettings);
     setText('queueTitleText', UI_TEXT.static.queueTitle);
+    setText('btnRetryFailed', UI_TEXT.static.retryFailed);
     setText('btnClear', UI_TEXT.static.clearQueue);
     setText('refreshText', UI_TEXT.static.refresh);
     setText('clipsHeading', UI_TEXT.static.clipsHeading);
@@ -74,6 +75,13 @@ function applyLanguageToStaticUI(): void {
     setText('partMinutesLabel', UI_TEXT.static.partMinutesLabel);
     setText('updateTitle', UI_TEXT.static.updateTitle);
     setText('checkUpdateBtn', UI_TEXT.static.checkUpdates);
+    setText('preflightTitle', UI_TEXT.static.preflightTitle);
+    setText('btnPreflightRun', UI_TEXT.static.preflightRun);
+    setText('btnPreflightFix', UI_TEXT.static.preflightFix);
+    setText('preflightResult', UI_TEXT.static.preflightEmpty);
+    setText('debugLogTitle', UI_TEXT.static.debugLogTitle);
+    setText('btnRefreshLog', UI_TEXT.static.refreshLog);
+    setText('autoRefreshText', UI_TEXT.static.autoRefresh);
     setText('updateText', UI_TEXT.updates.bannerDefault);
     setText('updateButton', UI_TEXT.updates.downloadNow);
     setPlaceholder('newStreamer', UI_TEXT.static.streamerPlaceholder);
diff --git a/typescript-version/src/renderer.ts b/typescript-version/src/renderer.ts
index ea4c477..24dc277 100644
--- a/typescript-version/src/renderer.ts
+++ b/typescript-version/src/renderer.ts
@@ -80,6 +80,9 @@ async function init(): Promise<void> {
         void checkUpdateSilent();
     }, 3000);
 
+    void runPreflight(false);
+    void refreshDebugLog();
+
     setInterval(() => {
         void syncQueueAndDownloadState();
     }, 2000);
diff --git a/typescript-version/src/styles.css b/typescript-version/src/styles.css
index 7da2527..e96c375 100644
--- a/typescript-version/src/styles.css
+++ b/typescript-version/src/styles.css
@@ -318,6 +318,15 @@ body {
     transition: all 0.2s;
 }
 
+.btn-retry {
+    background: #2a3344;
+    color: #d9e4f7;
+}
+
+.btn-retry:hover {
+    background: #33405a;
+}
+
 .btn-start {
     background: var(--success);
     color: white;
@@ -574,6 +583,19 @@ body {
     gap: 10px;
 }
 
+.log-panel {
+    background: #11151c;
+    border: 1px solid rgba(255,255,255,0.12);
+    border-radius: 6px;
+    padding: 10px;
+    max-height: 220px;
+    overflow: auto;
+    white-space: pre-wrap;
+    color: #b8c7df;
+    font-size: 12px;
+    line-height: 1.35;
+}
+
 .form-row input {
     flex: 1;
 }