Thank you for your comment, I find it reassuring there is hope, but I really have no clue how my machine could be “non-standard” (assuming you are also on Windows, as it does seem a Windows issue). I am a local administrator on my machine, it is not on a domain, I have a regular, simple 3-letter user name without special characters, I would assume my configuration is very similar to many others (windows 10, not 11).
I have also changed the permissions on the whole .julia folder as advised by oheil.
I am a bit skeptical on “very specific to your machine” because these problems seem to have been there for a long time and there is still (at least) one open issue on them (or at least similar problems):
(but this being said, I am of course willing to admit that the problems happen on some specific machines and not on all machines!)
Also, if it’s a permission issue, I don’t see why I am able to use PlotlyJS once, but then, if I restart Julia, it fails, until I also restart Windows.
You said you are teaching a course, do you give specific instructions on how to install Julia and the packages? Perhaps there is some mysterious order or way to install things?