EPUB Upload Errors
"File too large"
Cause: EPUB exceeds 100MB limit
Solution:
- Compress images within the EPUB
- Use online tools like TinyPNG before embedding
- Remove embedded fonts if not essential
- Resize images to web-appropriate dimensions
"Invalid EPUB file"
Cause: File is corrupted or not proper EPUB format
Solution:
- Run EPUBCheck validator
- Ensure file has .epub extension
- Re-export from your EPUB creation tool
- Don't rename .zip to .epub (must be properly packaged)
"Upload failed" or timeout
Cause: Network issue or browser problem
Solution:
- Check your internet connection stability
- Try a different browser (Chrome, Firefox, Safari)
- Disable browser extensions temporarily
- Clear browser cache and cookies
- Try uploading from different network
Cover Image Upload Errors
"Image too large"
Cause: Cover exceeds 10MB limit
Solution:
- Compress image using TinyPNG or similar
- Reduce image quality slightly (90% quality usually sufficient)
- Convert PNG to JPG if appropriate
- Resize if larger than 1600x2400px
"Invalid image format"
Cause: Unsupported file type
Solution:
- Convert to JPG, PNG, or WebP
- GIF and BMP not supported
- Use image editing software (Photoshop, GIMP, Canva)
"Image dimensions too small"
Cause: Cover below minimum requirements
Solution:
- Resize to at least 1600x2400px
- Maintain 2:3 aspect ratio
- Don't upscale low-res images (create new high-res version)
General Upload Tips
- Use stable internet connection (not mobile data)
- Don't close browser during upload
- Wait for progress bar to complete
- Check for success message before navigating away
- Keep original files as backup
Browser Compatibility
Recommended browsers:
- Google Chrome (latest version)
- Mozilla Firefox (latest version)
- Safari (latest version)
- Microsoft Edge (Chromium-based)
Still Having Problems?
If uploads continue to fail:
- Contact support with error message screenshot
- Include browser and OS information
- Describe exact steps when error occurs
- Support can review your files for issues