Error after i second click create backup

I install wp clone plugin in my wordpress.

when i first click create backup, it’s ok,

but when i second click create backup to create another backup,it’s show a error:

————————————————————–

The plugin encountered an error while copying files into the temp directory,the following error message was returned:

Error Message : Unable to create the temporary backup directory,please make sure that PHP has permission to write into the /home/wwwroot/www.—–.com/wp-content/uploads/wp-clone/ directory.

Temporary files created in **SITE-ROOT**/wp-content/uploads/wp-clone/wpclone_backup will be deleted.

——————————————————————

I try to reboot,and give the 777 permission to /wp-clone/,but it’s stall not work.

who can help me to deal with this?

My System Info is this:

Maximum execution time: 300 seconds
PHP version : 7.1.2
MySQL version : 5.5.53