Getting corrupted or empty zip by ZipArchive php

Try getting the full file path and name just before $zip->close();

$filename = $zip->filename;

And use that instead of $zipname when reading the file and getting the file size

This is my best guess. What's going wrong here is that in your array $files the values you're storing are probably not actual paths to files.

Remember: You can't pass URLs into $zip->addfile(), you need your actual files.