When you create backup or export csv files task failed with Error: cannot to pack error (solution below can be applied for 'Error during export!' and Can't unpack package issues)
Make sure sys_temp_dir in your php is writable
In the Admin → Settings → System → click PHP Info
in the top left. Search on page sys_temp_dir
value. If no value present please add it and make sure this folder is writable. You can ask your hosting support for help or try to configure php.ini yourself.
Even if you fail to compress backup file you still can find not compressed backup folder in the admin/system/backup/ directory.
Not compressed export file with csv can be found in admin/system/data/ directory on your server
Ask hosting support
this is related to your server setup, please contact your hosting to help you configure php or php modules