When administrators disabled features and users tried to access them
with the browser, we were responding with a 500 "Internal Server Error"
page, which in my humble opinion was incorrect. There was no error at
all; the server worked exactly as expected.
I think a 403 "Forbidden" code is better; since that feature is
disabled, we're refusing to let users access it.
We could also respond with a 404 "Not found", although I wonder whether
that'll be confusing when administrators temporarily or accidentally
disable a feature.
A similar thing might happen if we responded with a 410 "Gone" code.
Actually this case might be more confusing since users aren't that
familiar with this code.
In any case, all these options are better than the 500 error.