Fatal error: require_once(): Failed opening required '/home/customer/www/mydomain.com/public_html/libraries/import.legac

[aimlesslady]

I installed a backup (Akeeba) to a subdomain to check its integrity. I was able to log into the back end, but when I tried to see the front, I got this error:

Fatal error: require_once(): Failed opening required '/home/customer/www/mydomain.com/public_html/libraries/import.legacy.php' (include_path='.:/usr/local/php74/pear') in /home/customer/www/mydomain.com/public_html/includes/framework.php on line 17
Any insight what is causing this and how to fix it?
It is a Joomla 3 which we are migrating to Joomla 4 but I want to keep it in a subdomain until we are sure the migrated site is working properly.

[toivo]

Joomla cannot find or is unable to access the file libraries/import.legacy.php. Use File Manager from the cPanel provided by your host and check if the file is there and that its permissions are 644.

If the file is missing, expand the installation package for the version of Joomla 3 this site is using and copy the file to the web server.

[Webdongle]

Might be easier to test it on wamp. The subdomain might have path issues.
Is the subdomain folder level with or nested under the domain folder? If the later that can cause a path issue.

[aimlesslady]

The import.legacy.php file is in the libraries folder and the permissions are 644.
The subdomain is outside the public_html folder and has its own public_html folder where the files are installed.

[Webdongle]

There is normally only one public_html folder which is the server root
Usually the format would be
public_html
>/folderthatthedomainpointsto
>>/administrator etc
>/folderthesubdomainpointsto

Having the subdomain pointing to a folder outside of public_html folder can cause path issues. Best test the backup (and do the update) on wamp localhost.