MacBookPro Migration - All File Corrupted and actually they are not
I found the solution to this error (btw. the error message is "____ file is damaged and can't be opened. You should put it to trashbin."):

The gatekeeper function on Sierra is a bit altered and the last option "From any source" is not available for security settings. So I had to run this command in terminal:

sudo spctl --master-disable


Now the option "from any source" is available for gatekeeper. After I selected this option the files became available again.