Hi, I am having the exact same error when Installing Waninkoko's IOS249 for use with USB Loader.
I have a Wii JAP 4.1J with D2CKey - I accidentally updated it to 4.2J which disallowed playing non-JAP games, then I followed Modify Any Wii 4.2 & Below Guide to modify the 4.2J and then downgraded...