This is almost always caused by a problem with your connection to the internet.
Please go to the Wii Menu, go to Internet Settings and perform a connection test, to verify you are connected.
If you are connected to the internet and still experience this error, please contact us on our Discord Server.
This is a very general error, and can be caused by every single possible exception left unhandled.
Try restarting the Homebrew Browser, or redownloading it.