The issue was resolved. There was a firewall problem.

Hello, I have an error trying to convert a .vhdx file to an ESX Server (vCenter). The file is being created but is alway 0 KB of Size. The vCenter user has all administrative rights, so there should be no rights issue. 12/13 15:18:44.848 2d18 Facility ???ERROR: ESXVmdk::ParseFile: m_VixDiskLib_Open ...