Multiple file upload server error

Hi

I’ve instaled the plugin Multifile Upload Field for Contact Form 7 in order to been able to upload multiple files with Contact Form 7 but when I select the files and submit the spinning wheel spins forever and the form does not send the mail.

I’ve checked the console and I get this error: “Failed to load resource: the server responded with a status of 500 (Internal Server Error)”

Unfortunately the website is under maintenance mode so you might not be able to view the contact page.

Is there anybody that can help with this issue?

Thanks

The page I need help with: [log in to see the link]