Enter this URL into another tab to see a picture of what I'm referring to.

https://drive.google.com/open?id=0B7Chqpqv7MrHUXBBcnBNc19GcHVsMFhmeFFBczk2dWs0NnFZ

When I tried to go online on Mario Kart Wii, this image always pops up. I've never heard of this error happening before, and I'm unsure of what's wrong with my system for this to happen. I have successfully accessed Mario Kart Wii online before using the Homebrew Channel, and I did everything the same way here, and for some reason, this image has kept popping up for a while now. If anyone knows what this means or what I can do about it, please tell me.

As of November 2018, players are required to update their game to continue to play online: wiimmfi.de/update

What method are you using to connect to Wiimmfi? You either need to re-patch the game (ISO) or re-download a new patcher (discs).

I'm pretty sure I'm using either MrBean's Homebrew Auto Wiimmfi Patcher or a patched WBFS. The image linked below is how I identified what method I'm using, though I'm not sure if that's accurate.

https://drive.google.com/open?id=0B7Chqpqv7MrHUUNaQ0Z6UVBtVnRIcHVqMGZxeU9rTkw0WXQ0

If you are using that patcher you just need to redownload the new updated version and use that instead: wii.guide/assets/files/autowiimmfipatcher-0.6.zip

Thank you. I tried what you suggested last night, and I am now able to access online again, so the solution you posed was successful.