[ cut ]
License accepted. For batch installation add
--accept-license=56be48f923303c8cababb0bb4c478284b688ed23f16d775d729b89a2e8e5f9eb
to the VBoxManage command line.

0%...
Progress state: NS_ERROR_FAILURE
VBoxManage: error: Failed to install "/home/topolinik/Scrivania/Oracle_VM_VirtualBox_Extension_Pack-5.2.30.vbox-extpack"
VBoxManage: error: The installer failed with exit code 1:
VBoxManage: error: Details: code NS_ERROR_FAILURE (0x80004005), component ExtPackManagerWrap, interface IExtPackManager
VBoxManage: error: Context: "RTEXITCODE handleExtPack(HandlerArg*)" at line 1211 of file VBoxManageMisc.cpp