# C++ toolchain problem (Mac OS X Mojave)

**URL:** <https://discourse.mc-stan.org/t/c-toolchain-problem-mac-os-x-mojave/14870>\
**Category:** RStan\
**Tags:** installation\
**Created:** [May 5, 2020, 2:31pm UTC](https://discourse.mc-stan.org/t/c-toolchain-problem-mac-os-x-mojave/14870 "2020-05-05T14:31:28Z")\
**Posts on this page:** 1\
**Showing post:** 6

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**Author:** ![wds15](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/wds15/32/908_2.png) [@wds15](https://discourse.mc-stan.org/u/wds15)\
**Post date:** [May 5, 2020, 3:40pm UTC](https://discourse.mc-stan.org/t/c-toolchain-problem-mac-os-x-mojave/14870/6 "2020-05-05T15:40:48Z")

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I think it was this one:

> [@R 4.0.0 and CRAN MacOS binaries](https://discourse.mc-stan.org/t/r-4-0-0-and-cran-macos-binaries/13989/19):
>
> I also was having issues with multiple chains running in parallel in MacOS using latest R-4.0.0 and RStan. I’ve found out that this is a problem of the package parallel from R-4.0.0 I’ve found this [recently issue](https://github.com/rstudio/rstudio/issues/6692) in RStudio’s GitHub that solved my problem: cl \<- parallel::makeCluster(2, setup\_strategy = "sequential") If this works, you could add the following to your ~/.Rprofile until this is fixed in R/RStudio: ## WORKAROUND: https://github.com/rstudio/rstudio/issues/6692 ## Revert to 'se…

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