This is not a corrupt backup. As you said, you can restore on another host. Moreover, I can see that it does read the very first file added to the backup archive at backup time, it just cannot write it to the disk.
I believe this is a problem with the ownership and permissions of the html folder which needs to be addressed by your host. Remember that your web server runs under a user and group. Whether it can write to disk depends on what this user and group is and what are the ownership and permission settings for the html folder it tries to write into.
On modern servers set up correctly, each site runs under its own user and group. It does not run under the Apache user/group (apache:apache, nouser:nogroup or www-data:www-data are the usual user/group settings used for Apache in the most common Linux distributions used on commercial servers, i.e. RedHat and Debian derivatives including CentOS, Rocky Linux, and Ubuntu Server). If the site —therefore PHP itself— runs under its own user but the html folder is owned by apache:apache with 0755 permissions then the user PHP runs under can only read from that folder, not write to it, hence the error message.
This is already explained in https://www.akeeba.com/documentation/akeeba-kickstart-documentation/kscantextract.html and https://www.akeeba.com/documentation/akeeba-kickstart-documentation/kstslive.html.
However, I do NOT recommend going the FTP route. It's best to ask your host for support.
As to whether I have experience with that: yes, I do :) I have a test server on a commercial IaaS company running Ubuntu Server. NginX (that server does not use Apache) runs as www-data:www-data. However, I create a new PHP-FPM pool for each test site running as its own user and group www-data, e.g. test3:www-data. I have one folder for each hosted site under /var/www e.g. /var/www/test3. This folder has ownership test3:www-data and permissions 0755. This isolates writing from one site to the other (but not reading — I don't care about that since it's a test server).
If I had left each folder with the default ownership of www-data:www-data and permissions 0755 PHP would not be able to write to these folders. I actually did that, by accident, when setting up the server and I of course could not restore backups; I had the same error you see. Changing the ownership of the folders to match each hosted site's PHP-FPM pool's user did the trick.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!
