Positron fails at startup

[Bernard_Forgues]

Hi, when launching Positron 2025.11.0 build 234 on a Mac BookPro (MacOS 26.1 (25B78)), I get the following error message:
R 4.5.2 failed to start up (exit code -1)
The process exited abnormally (signal: 6 (SIGABRT))
The issue is not with R, which works perfectly with RStudio.
Thanks.

[petetronic]

Hi Bernard, I wasn't able to reproduce this issue with the same macOS, Positron and R version as you reported.

Positron uses the ARK language runtime for R sessions, that team may be able to help you track down what is different about your R environment. Try checking the architecture of your R 4.5.2 installation to ensure it is arm64, or consider whether it is crashing based on something specified in a .Rprofile, renv, .Renviron, etc. You could also log an issue at the ARK GitHub repository.

You could also try the "dailies" update channel to see if a more recent build of Positron + ARK has addressed this issue, see:
Updating Positron to Daily Builds docs

Here's more details on the version I tested locally:

macOS Tahoe 26.1 (25B78)

Positron Version: 2025.11.0 build 234
Code - OSS Version: 1.105.0
Commit: 807acdfca108da6b9b2d96452fe047238da1bd9f
Date: 2025-10-31T23:02:00.803Z (4 wks ago)
Electron: 37.6.0
Chromium: 138.0.7204.251
Node.js: 22.19.0
V8: 13.8.258.32-electron.0
OS: Darwin arm64 25.1.0 // Note I believe this was the build environment

R version 4.5.2 (2025-10-31) -- "[Not] Part in a Rumble"
Copyright (C) 2025 The R Foundation for Statistical Computing
Platform: aarch64-apple-darwin20

[Bernard_Forgues]

Hi Pete,
Thanks a lot for the super fast response, all the more on a Thanksgiving week-end (if I understood correctly).

I have exactly the same version of R as you:
R version 4.5.2 (2025-10-31) -- "[Not] Part in a Rumble"
Copyright (C) 2025 The R Foundation for Statistical Computing
Platform: aarch64-apple-darwin20

I'm not sure how to check if the architecture of my R is arm64, though.

Unfortunately, updating to the latest daily build didn't solve the issue.

I've just logged the issue with ARK.

Thanks!
Bernard

[jonathan]

For anyone following along at home, this issue was resolved; the problem was an old Intel version of Homebrew that was putting its bash on the PATH, causing portions of Positron to run in x86 (not arm64) mode. The fix was to remove this old Homebrew installation.

More details in the ark issue: Positron fails to start R · Issue #971 · posit-dev/ark · GitHub