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WebP Conversion Failing

If WebP conversion does not complete or batch processing stalls, it is usually caused by server limitations or unsupported image types.

35.1 Problem #

You may notice:

  • Batch conversion stops midway
  • WebP files are not generated
  • AJAX scanner fails silently

Technical Context #

  • Batch processing runs via AJAX requests
  • Debug logs are written to:
wp-content/cnc-webp-debug.log
  • Failures are typically logged for diagnostics

Common causes include:

  • Unsupported image MIME types
  • File permission issues
  • Large image files causing execution timeout

Supported formats:

  • image/jpeg
  • image/png

35.2 Solution #

1. Verify File Permissions

  • 0755 for folders
  • 0644 for files

2. Confirm Image Format

  • Ensure images are JPEG or PNG
  • Exclude unsupported formats (SVG, GIF, BMP, etc.)

3. Check Image Library Support

  • Confirm GD supports WebP
  • Or ensure Imagick is compiled with WebP support

4. Increase PHP Limits (if needed)

  • Increase memory_limit
  • Increase max_execution_time

After applying fixes:

  • Clear cache
  • Re-run WebP conversion

35.3 Best Practice Recommendation #

  • Optimize large images before uploading
  • Run conversion in smaller batches on shared hosting
  • Monitor debug log for repeated failures

Proper server configuration and supported image formats ensure smooth and reliable WebP conversion.

Updated on March 12, 2026