I got the same error running Windows 8 Pro N. The run as Administrator didn't work for me so i did something else.
I solved it by going to C:\ProgramData\VMware\VMware vCenter Converter Standalone, right click on the "ssl" folder, on security and clicked on "Advanced" button. When it opened new window i went on "Auditing" tab, clicked on button Continue, and there i added user. You do that by clicking "Select a principal", typing in the user name, and then tick on check box sayin "Full control". By doing that, i was able to convert my physical machine. Image may be NSFW.
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