I had reveal working fine with cider, then without upgrading anything it stopped working with this error. I get this even in an empty project with just the nrepl and reveal deps:

Syntax error (UnsupportedOperationException) compiling at (cljfx/api.clj:72:1).
Unable to open DISPLAY

the deps.edn in my minimal repro is just

{:deps {vlaaad/reveal {:mvn/version "1.2.182"}}}

and cider run this to initialize the nrepl server:

[nREPL] Starting server via /usr/local/bin/clojure -Sdeps '{:deps {nrepl {:mvn/version "0.8.2"} refactor-nrepl {:mvn/version "2.5.0"} cider/cider-nrepl {:mvn/version "0.25.4"}}}' -m nrepl.cmdline --middleware '["refactor-nrepl.middleware/wrap-refactor", "cider.nrepl/cider-middleware", "vlaaad.reveal.nrepl/middleware"]'

the above is trying to jack in; launching the nrepl process from the command line and connecting to it from cider works fine

@euccastro Something that affects X11 must have changed on your system -- that's what "Unable to open DISPLAY" means.

it's weird that that won't stop reveal from launching alright from the shell

Maybe your emacs is running in some sort of terminal-only container that does not have access to display?

emacs is running in window mode