I am using the windows version of emacs that includes AuTeX and ESS from Vincent Goulet. I was using an older version of this packaging with a couple different versions of R. I recently installed the new version of R (4.0.2) and am attempting to connect it to emacs. I have added the directory that contains the R version 4.0.2 to my path and also added the folder that contains the 3 different version of R that are installed on my machine. When I open a .R file and open an instance of R it opens an R version of 4.0.2. However, when I go to the ESS menu and try to start a new process (ESS>Start Process>Other>) the options that I see are R-3.4.4-32bit, R-3.4.4-64bit, R-3.5.1-32bit, R-3.5.1-64bit. Similarly, if I try to complete M-x R the options do not include the R-4.0.2 version. Also when I tried M-x R-newest I got the error: Symbol's function definition is void R-newest. I have tried again to run M-x R-newest but now it stats [no match].

I was previously using an older release version Vincent Goulet's emacs but updated it while attempting to fix this issue. The current version I am using is emacs 26.3 with ESS 18.10.2. I have tried changing the PATH variable in numerous ways to include/exclude the directory of the R verions for the older versions. I tried looking in the lisp and changing some custom variables in my .emacs file to no avail, such as

    ("C:/Program Files/R/R-4.0.2/bin/x64/Rterm.exe" "C:/Program Files/R/R-4.0.2/bin/i386/Rterm.exe" "C:/Program Files/R/R-3.5.1/bin/i386/Rterm.exe" "C:/Program Files/R/R-3.4.4/bin/i386/Rterm.exe" "C:/Program Files/R/R-3.5.1/bin/x64/Rterm.exe" "C:/Program Files/R/R-3.4.4/bin/x64/Rterm.exe")))

How do I get ESS to recognize R-4.0.2 (both 32bit and 64bit) and add it to the list of available processes?

1 Answer 1


Check the value of ess-r-runner-prefixes. Until recently, it did not include R-4. You can customize it yourself, or if you install the latest/current version of ESS the default value should work.

See the responses to this email on the mailing list for more details:



This is a known issue, and Vincent Goulet's latest release (as of September 17, 2020) includes a fix.

  • When I try to check the value of ess-r-runner-prefixes it says no match. I do have an ess-r-created-runners though. It showed the 2 older version of R. I've tried reinstalling ess from melpa commit 0728c6fdf8e13f10ee50b27fb3f39e7c229f05b1 and now ess-r-created-runners is not matching. Sep 16, 2020 at 21:45
  • ess-r-runner-prefixes wasn't in ESS 18.10.2. That version was released two years ago, before R 4 was available. You can get a more recent ESS by installing it from MELPA
    – Tyler
    Sep 17, 2020 at 19:26
  • @user3653085 this problem is fixed in the Vincent's latest release!
    – Tyler
    Sep 17, 2020 at 20:46
  • Awesome! Thanks for leting me know it works like a charm now Sep 17, 2020 at 23:55

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