I am having issues, where do I leave a bug report?

Please leave bug reports either on Juno.jl GitHub repository or at Julia's discussion forum under the Tooling ▶ Juno category.

Juno could not be started.

Go to Packages > Juno > Settings and change Julia Path to point to the Julia binary.

The installation of some Atom packages fails. What can I do?

It is possible that your Antivirus Software prevents certain files to be downloaded or executed that are necessary for Juno to function. Consider disabling antivirus software's real time monitoring for the duration of the installation. For certain scanners (Avast and McAffee) it might also be necessary to exclude


from the real time monitoring after installation. This is an upstream issue which should hopefully be resolved soon.

Juno doesn't work properly after an Atom update. What do I do?

Check whether you have a little red bug symbol in the status bar (lower right):

native bug

If so, click on it and then click on Rebuild Packages:

native update

Restart Atom and you should be good to go!

Juno doesn't work properly after some Atom packages were updated. What do I do?

There's a chance the update of julia-client failed. To get a clean re-install while preserving any setting you might have changed, try the following steps:

  1. Close all Atom instances.
  2. Start a terminal (e.g. cmd on Windows or the Terminal App on MacOS)
  3. Execute apm uninstall julia-client.
  4. Execute apm install julia-client.
  5. Start Juno. Everything should work again.

The integrated REPL/terminal is unbearably slow. How do I fix it?

Enable the Fallback Renderer option in the Terminal Options in julia-client's settings and restart Atom for good measure.

Some Juno package is using the wrong precompile cache, what do I do?

This problem manifests itself in errors like:

WARNING: Method definition
WARNING: Module Juno with uuid 738353145462472 is missing from the cache.
ERROR: LoadError: Declaring precompile(false) is not allowed in files that are being precompiled.
ERROR: LoadError: Failed to precompile Atom to C:\Users...

One way this can occur is from updating Julia versions. However, this has a very easy fix. Go into the Julia REPL (not the Juno console in Atom, but the actual Julia terminal window) and type in the command:

using Atom

That will force Julia to re-compile all of the cache files and should fix the problem.

I am having a problem running Juno with an older version of Julia, why?

Juno is under rapid development, so it's expected that previous versions may not be compatible with the Atom packages overtime. Julia will automatically use older versions on the Julia-side packages, but Atom will always give you the most up-to-date packages it knows about, which causes this issue. The easy way to solve this is to always use the current Julia release. Otherwise, resort to the Developer Installation Instructions for the Atom packages and use git to checkout an older version. This requires some git know-how, so it's only recommended if the older version of Julia is truly necessary.

How do I use Juno with the Julia Nightly version?

If you want to use Juno with the nightly version use caution: this package is under rapid development so do so at your own risk. That being said, the Julia nightly should work using the Developer Installation Instructions. Note that this will require you to be on master for the Julia and Atom packages, so things will be changing likely before documentation changes.

How do I execute code on Juno startup?

Much like Julia has its ~/.julia/config/startup.jl file for executing code on startup, Juno will execute code contained in ~/.julia/config/juno_startup.jl after Julia has been booted and a connection with the editor is established. This allows running code on startup that queries the frontend, e.g. Juno.syntaxcolors.