Class not found on Webserver (Digital Ocean)

HI,

I'll get this error on all pages in which I use a Widget Package:

Class 'app\widgets\SidebarCurrent' not found

All my Widgets have been working today and now the class cannot be found. I have no idea what could have caused this problem.

My server structure (Digital Ocean & Forge) looks like this http://www.directupload.net/file/d/3884/xpugejnh_png.htm

Locally (XAMPP) all is working well.

Can someone give me a hint, what happens here?

Regards Andreas