von SAMIR ELFADIL.
I asked the hosting provider for ssh acces privilege in order to do your suggestion, when I run php backup.php from /admin/cli the following error message appers:
PHP Parse error: syntax error, unexpected ':', expecting ';' or '{' in lib/classes/component.php on line 1163
I created file phpinfo.php in webroot dir and show php 7.2, I think such error show up when using php5.6 but the info file show different version.
I think this is the core problem.