The browser displays a connection error.

[19231224lhr]

like this picture, all things have passed, but the browser has a white paper.

[jhump]

grpcui uses a Go library to open the browser, and that library delegates to xdg-open. If your Linux install does not include this program you could add it by installing xdg-utils:

sudo apt-get install --reinstall xdg-utils

If you're not using Debian or Ubuntu, you'd need to use a different incantation than above.

One thing I noticed is that the latest version of the browser package also supports programs named x-www-browser and www-browser. Could you check to see if either of those is in your PATH? If so, this may be as simple as updating the dependency in grpcui, via something like so in this repo:

go get github.com/pkg/browser@master