I recently had a USB harddrive failure on my Wii U, and I'm in the process of using a data recovery company (and it's not cheap). I've realised that I will have problems getting the retrieved data from my computer (Mac or PC) to the Wii U system memory, as the computer says that the media (usb memory stick or sd card in a USB adapter) is in a format it can't access (the format is the format the Wii U uses).

I can only think of using usb or sd card memory as a way of transferring the save data to the Wii U system memory, but I have this problem of the computer not understanding the formatting and therefore not being able to transfer the files to the usb stick/sd card.

Is there any other way I can transfer the save files, wifi or something, or some way of getting around the computer not liking the Wii U formatting? If I can't get my save files transferred I will lose 55 hours of MArio Kart 8 progress, and will have to start again!

No. They did this to stop the rampant SD card-based "hacking" from the Wii. You are out of luck and just paid a bunch of money for absolutely nothing. Sucks, but it is what it is. Not even through homebrew is it possible...yet.

I don't get it. Aren't the save files on the WiiU itself?

Oh well, I've learned the hard way to keep them on the system memory from now on.

@LemonSlice If a usb memory device (like a memory stick or hard drive is detected by Wii U OS it puts save files there by default). I even copied the hard drive save files to the system memory as a kind of backup if anything happened to the harddrive when I sent the Wii U & harddrive to Nintendo for a problem with the Wii U console that needed repairs. I got the console back (repaired) and hardrive and moved the save files to the hardrive, so it was in the setup I had before. I was re-downloading my digital copies of games to the hardrive (as nintendo had to wipe them off) when the drive started making funny noises and stopped working. The data recovery company said the heads were misaligned and would need parts to be replaced. They charged me £240 for the parts and work done so far, if I had known then what I know now about Nintendo taking action on sd card hacking I would of told the data recoverer to not bother trying to rescue it.

I thought about not bothering with usb harddrives again, but it will be a problem having to delete older games to make way for new ones. A drives with less storage capacity will not cost as much as my current one, and I'll only store downloaded games on it.

if only the hard drive crashed I feel like you can just redownload everything using your wii-u. It's a presumption seeing as I haven't done this myself, but when my data was corrupted on my wii sd card I was able to redownload everything onto a new sd card from the wii shop channel. Suppose I could be totally wrong