backup.php Error local datafile filesize is not an integer number of 4 bytes #37

Hi all, I'm trying to backup emoncms v.8.4.0 feeds which is on a site that offers hosting service.
After configuring the backup.php file with apikey, directory and site address, launching the file after a while I get the error written in the subject of the problem.
Even relaunching the file always gives the same error.
Help please and happy sarata.
Mauro