Error shown
File: C:\wamp\www\harmony2\vendor\ezsystems\ezpublish-kernel\eZ\Publish\Core\IO\Handler\Legacy.php
Line: 530
Message: Argument '$path' is invalid: Storage directory 'var/ezdemo_site\storage' not found in var/ezdemo_site/storage/images/products/vegetables/254-8-ger-DE/Gemuese.jpg

Problem
The storage directory file is set to "var/ezdemo_site
storage". The backslashes on Windows makes the comparison with the file path not working.

THE WORKAROUND
In constructor of the "vendor\ezsystems\ezpublish-kernel\eZ\Publish\Core\IO\Handler\Legacy.php" change to:

$this->storageDirectory = str_replace( DIRECTORY_SEPARATOR, '/', $storageDirectory );