Please check your configuration ~/jruby_art/config.yml, if you get the following error (or similar)

LoadError: load error: C:/jruby-9.1.15.0/lib/ruby/gems/shared/gems/jruby_art-1.4.6/lib/jruby_art/app --java.lang.NoClassDefFoundError: processing/core/PApplet

It means the program can't find the processing root and you should make sure that

PROCESSING_ROOT: /home/tux/processing-3.4

matches your system (typical linux shown above for user tux) for windows it may be safer to use quoted string, especially if you have spaces in your path.

Ensure that you are using the recommended versions of processing(k9 setup check), jruby (jruby -v) and java (java -version) Provide JRubyArt version that you are using (k9 --version) Provide your operating system and platform (e.g. uname -a, and/or java -version output if relevant)

Describe your expectation of how JRubyArt sketch should behave. Provide a problematic JRubyArt sketch or a link to an example repository.

Describe or show the actual behavior. Provide text or screen capture showing the behavior.

eg installation issue (just use this header and explain the problem as best you can)