The 2.3 CNI installer fails with the following error if the /etc/cni/multus/net.d/ directory doesn't exist:

 error   Installer exits with open /host/etc/cni/multus/net.d/v2-3-istio-cni.kubeconfig.tmp.841118073: no such file or directory

The same issue might also be present in v2.2 and earlier versions of the installer, but it doesn't manifest itself because the v2.2 istio CNI DaemonSet runs multiple versions of the installer (1.1, 2.0, 2.1 and 2.2). The 2.0 container (and possibly 1.1) creates the dir, allowing all other versions to work properly.

We moved the 2.3 CNI installer into a separate DaemonSet. If you deploy a 2.3 SMCP, only this DaemonSet is installed. If the directory doesn't exist, nobody creates it. The 2.3 installer simply fails with the error above.