What could this be? Transfer error code 16

[Boniforti Flavio]

> This looks like an application is running where the backup is 
> to be made. The application opens and locks the files 
> with an exclusive lock and the rsync program must then wait 
> until it is freed by the application or times out.
> 
> This is a typical problem under Windows. Can you ask the user 
> to close the application?

In fact, that was the issue it seems. Thanks.

Flavio.