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Common Issues

This guide covers the most frequent problems users encounter and their solutions.
Problem: The Python backend fails to start, or you see an error about permissions.Solution:Make the engine binary executable:
chmod +x ./backend/dist/engine
If you’re running from a packaged app, check the app permissions in System Preferences > Security & Privacy.Additional Steps:
  • Ensure you have Xcode Command Line Tools installed: xcode-select --install
  • For Apple Silicon Macs, verify the binary was built for the correct architecture
Problem: The engine.exe process fails to launch or crashes immediately.Solution:
  1. Check Windows Defender hasn’t quarantined the executable
  2. Run the app as Administrator (right-click > Run as administrator)
  3. Install Visual C++ Redistributable if missing
  4. Check the app’s userData folder for crash logs:
    • %APPDATA%\universal-novel-scraper\
Problem: When building the engine, you get module import errors.Solution:Ensure PyInstaller runs inside the virtual environment with all dependencies:
cd backend
source venv/bin/activate  # or venv\Scripts\activate on Windows
pip install -r requirements.txt
python -m PyInstaller --onefile --windowed --name engine api.py
Verify these packages are installed:
  • fastapi
  • uvicorn
  • ebooklib
  • pydantic
  • requests
Problem: The scraper starts but finds 0 chapters or stops after the first one.Solution:
  1. Check the provider script - Make sure you have the correct provider installed for your target site
  2. Try manual mode - Enable “Show Browser Window” in Settings to see what’s happening
  3. Cloudflare Protection - Enable “Cloudflare Bypass” mode and manually solve challenges
  4. Site Changes - The website may have changed its HTML structure. Check for provider updates in the Marketplace
If a provider consistently fails, it may be outdated. Community providers are maintained independently and may need updates when sites change their layouts.
Problem: Chapters scrape successfully but EPUB creation fails.Solution:
  1. Check the backend logs for specific errors
  2. Verify there’s sufficient disk space in the userData directory
  3. Ensure chapter data isn’t corrupted: 
    # Check the progress file
cat ~/Library/Application\ Support/universal-novel-scraper/output/jobs/[job_id]_progress.jsonl
  4. Try finalizing manually via the History tab
Common Causes:
  • Invalid cover image format
  • Special characters in novel title
  • Corrupted chapter data
Problem: Every chapter triggers a Cloudflare challenge, slowing down the scrape.Solution:
  1. Enable “Cloudflare Bypass Mode” in the Download settings
  2. Increase the delay between chapters (Settings > Scraper Timing)
  3. Use the “Show Browser Window” option to manually solve challenges
  4. Some sites require manual cookie authentication - solve one challenge, then scraping should work
Tips:
  • Cloudflare learns from your behavior - random delays help
  • Don’t scrape too fast - use 2-5 second delays
  • Keep the browser window focused when solving challenges
Problem: Clicking “Install” or “Update” on providers does nothing.Solution:
  1. Check your internet connection
  2. Verify the provider repository URL is accessible
  3. Clear the provider cache:
    • Close the app
    • Delete providers/ folder in userData
    • Restart and reinstall providers
  4. Check browser console for errors (View > Toggle Developer Tools)
Problem: The EPUB file is created but won’t open in readers.Solution:
  1. Verify file integrity - check file size (should be > 10KB)
  2. Validate with EPUB validator tools like EPUBCheck
  3. Try different EPUB readers (Calibre, Apple Books, Google Play Books)
  4. Re-download from Library > Export
Known Issues:
  • Some readers don’t support all cover image formats
  • Very long chapter titles may cause formatting issues
Problem: Backend fails to start because port 8000 is occupied.Solution:Find and kill the process using port 8000:macOS/Linux:
lsof -ti:8000 | xargs kill -9
Windows:
netstat -ano | findstr :8000
taskkill /PID [PID_NUMBER] /F
Or modify backend/api.py to use a different port and update the frontend API calls.

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Platform-Specific Issues

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macOS

Problem: “App can’t be opened because it is from an unidentified developer.”Solution:
  1. Right-click the app > Open
  2. Click “Open” in the dialog
  3. Or disable Gatekeeper temporarily: 
    sudo spctl --master-disable

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Windows

Problem: “Windows protected your PC” warning appears.Solution:
  1. Click “More info”
  2. Click “Run anyway”
  3. Or add exception in Windows Security settings

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Linux

Problem: App won’t start due to missing system libraries.Solution:Install required packages:Ubuntu/Debian:
sudo apt-get install libgtk-3-0 libnotify4 libnss3 libxss1 libxtst6 xdg-utils libatspi2.0-0 libdrm2 libgbm1 libxcb-dri3-0
Fedora:
sudo dnf install gtk3 libnotify nss libXScrnSaver libXtst xdg-utils at-spi2-atk libdrm mesa-libgbm libxcb

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Debug Mode

For advanced troubleshooting, enable debug logging:
  1. Open Developer Tools: View > Toggle Developer Tools
  2. Check Console tab for errors
  3. Network tab shows API calls to backend
  4. In main.js, backend stdout/stderr logs appear in terminal

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Getting Help

If your issue isn’t listed here:
  1. Check GitHub Issues for similar problems
  2. Open a new issue with:
    • Operating system and version
    • App version
    • Complete error messages
    • Steps to reproduce
  3. Include logs from:
    • Developer console
    • Backend engine output
    • userData directory logs
Never share personal information or authentication tokens when reporting issues.