This error message is displayed during import or export of a machine under vCenter Converter plugin and sometimes with the standalone converter.
If a user environment has versions of VI Client 2.5 Update 1, Update 2, Update 3, or Update 4 that coexist with vSphere Client 4.0, and you install the vCenter Converter 4.1.0 client plug-in, when you start the vCenter Converter Import or Export wizard, the vSphere Client session is terminated abruptly. An OpenSSL DLL conflict between the VI Client versions and the vCenter Converter 4.1.0 client plug-in causes this problem.
Workaround: Go to the Launcher folder in the VI Client install directory, for example, C:\Program Files\VMware\Infrastructure\Virtual Infrastructure Client\Launcher, and delete the following DLL files from that location:
For this workaround to function correctly, you also need to ensure that no additional copies of OpenSSL DLL files with different versions exist in the system path.
Also, make sure that the %TEMP% path does not have any non-english characters in it e.g. if you are using French / German / Spanish Windows OS. If you are, create the C:\TEMP directory and update your environment variables to point here.
Note for ESX users: if the fixes above do not work for you, try uninstalling all your VMWare clients, reboot and install the vCenter client from your vCenter’s https page. Now try and access your host using the vCenter client – you will connect and be prompted to download and install the Infrastructure client – if you do it this way then you shouldn’t have any issues.