VMs fail to boot with error: "SR_BACKEND_FAILURE_46, The VDI is not available"

VMs fail to boot with error: SRBACKENDFAILURE46 ; The VDI is not available opterr='INTERNALERROR', 'Syserror\\n "/var/run/nonpersistent/forkexecd/executecommandgeterrc83846.log: Too many open files"';...