restore problem - missing configuration File (conf.json)

Good morning from Greece
Strangely today I tried to revert to restore a website and got an error:

"tar unexpected EOF in archive
tar error is not recoverable: exiting now
 and at the end "missing configuration File (conf.json)"

I deleted whole newbackup folder and created a manual backup -- restoring back ---> same error
I use the NEW BACKUP (BETA)