"FileIntegrityCheck" error on beginning the installation

Hi all,
I just started the installation by clicking the first red “next” button only to see this:

Error while resolving diagnostics.optional[0]. No entry or class found for 'Piwik\Plugins\Diagnostics\Diagnostic\FileIntegrityCheck'

Well, that failed quickly. Can anyone help? Is this a bug or a configuration issue?

Looks like you are missing some files, did you try to re-download PIWIK and re-upload it to your server?

Thanks, it was indeed a problem with corrupted/missing files during FTP transfer.