I asked last year about this issue and got this response.
RFE #160907
Hello Alexander, Many released back (well before Houdini 20.0), or development team made the decision that Houdini help files will not launch from the external web browser. You can open these help files from the internal browser, inside of Houdini. And launch the files directly from houdini/help/examples
It's... a really weird decision. I've read the javascript code in the help page, and clearly it was originally allowed to load example files from external browser. Don't know why they changed their mind.
while not an answer to the exact question, you should also be able to find all examples for any node in the recipe menu, which I find much faster to explore node examples than going through help
tamte while not an answer to the exact question, you should also be able to find all examples for any node in the recipe menu, which I find much faster to explore node examples than going through help
That's good to know! Glad that I don't need to use that sluggish embedded browser