I have a strange problem, which I have no idea what it comes from.

cider stopped working for me, but it's probably not his fault

ribelo@ribelo-xps ~/c/sctrl (master)> clj -R:nREPL -m nrepl.cmdline
-R is deprecated, use -A with repl, -M for main, or -X for exec
WARNING: When invoking clojure.main, use -M
Execution error (FileNotFoundException) at clojure.main/main (main.java:40).
Could not locate nrepl/cmdline__init.class, nrepl/cmdline.clj or nrepl/cmdline.cljc on classpath.

@huxley what's in the REPL alias in deps.edn?

:nREPL
            {:extra-deps
             {nrepl/nrepl {:mvn/version "0.8.3"}}

I checked different versions of Java, different versions of Clojure and different versions of nREPL. Always the same error.

You should definitely be using -M not -R btw

ribelo@ribelo-xps ~/c/sctrl (master) [1]> clj -M:nREPL -m nrepl.cmdline
DEPRECATED: Libs must be qualified, change criterium => criterium/criterium (/home/ribelo/.clojure/deps.edn)
Execution error (FileNotFoundException) at clojure.main/main (main.java:40).
Could not locate nrepl/cmdline__init.class, nrepl/cmdline.clj or nrepl/cmdline.cljc on classpath.

That should work. Can you try clj -Srepro ...? Also, just a sanity check: is :nREPL under the :aliases key in your deps.edn?

removing $HOME/.m2 solved the problem