cPanel team has released v120.0.12 in which they upgraded 3rd party PHP binary to PHP 8.3 and it does not include ionCube loaders.
Note: This issue has been resolved in cPanel v120.0.14 update. If you still face the issue please open a support ticket with us.
Softaculous requires ionCube loaders and due to the above mentioned release Softaculous does not work on cPanel v120.0.12
cPanel team has opened a bug report here :
https://support.cpanel.net/hc/en-us/articles/24660301532439-cPanel-internal-PHP-fails-to-load-Ioncube-on-cPanel-version-120
Once they release a fix Softaculous should work automatically without any action required.
Workaround
You can execute the following command as a workaround to load ionCube until cPanel team releases as fix :
wget -O /usr/local/cpanel/3rdparty/php/unversioned/ioncube/ioncube_loader_lin_8.3.so https://files.virtualizor.com/ioncube/64/ioncube_loader_lin_8.3.so
That’s it! Softaculous should work now.
Once cPanel releases a patch with ionCube loaded it should overwrite the ionCube file we just downloaded and then the 3rd party PHP binary will load the ionCube loaders provided by cPanel.