# Intermittent failure of RStudio "Check on Save"

**URL:** <https://discourse.mc-stan.org/t/intermittent-failure-of-rstudio-check-on-save/13451>\
**Category:** Modeling\
**Created:** [March 2, 2020, 4:15pm UTC](https://discourse.mc-stan.org/t/intermittent-failure-of-rstudio-check-on-save/13451 "2020-03-02T16:15:01Z")\
**Posts on this page:** 1\
**Showing post:** 9

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**Author:** ![bgoodri](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/bgoodri/32/4451_2.png) [@bgoodri](https://discourse.mc-stan.org/u/bgoodri)\
**Post date:** [March 4, 2020, 6:44am UTC](https://discourse.mc-stan.org/t/intermittent-failure-of-rstudio-check-on-save/13451/9 "2020-03-04T06:44:42Z")

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I am pretty sure that if you have the C++ toolchain installed correctly like in

> [@Dealing with Catalina IV](https://discourse.mc-stan.org/t/dealing-with-catalina-iv/13502):
>
> If you are trying to install the pkg from in order to get the C++ toolchain setup on Catalina, then to open it you apparently have to hold down Ctrl while clicking on the installer file that you downloaded. At that point it should look like [[image] ](https://user-images.githubusercontent.com/833642/68826173-5f151400-0662-11ea-8a57-418f88f41ea3.png) and clicking Open will get it going. You probably need to have R 3.6 or later for things to work smoothly. Also, you will probably have to install rstan and related packages from source, via instal…

then if you install rstan from source, the exceptions thrown by the parser in the event of an invalid Stan program should be handled appropriately, rather than what you are seeing.

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