Updated R to 3.6 and all hell broke loose

Summary:

Updated R and Rstudio, and all hell broke loose

Description:

I've been running the rethinking package, which uses rstan, for about 6 months - no problem. I updated R today, and all of a sudden things have gone haywire.

I uninstalled and re-installed rstan (and all other packages, for that matter), including updating Rtools. No luck. When I try to run the schools example directly from the Rstan "getting started" page, I get the error listed below

The C++ toolchain passes the test
I have also tried disabling the C++ toolchain configuration (which is noted to sometimes cause problems). No luck. Exact same issue.

I have de-installed and re-installed from scratch (R, then Rstan, then other toolboxes), but still no luck.

Any advice would be GREATLY appreciated. BTW - I'm just an ordinary scientist, not a developer or c-scientist ...so I would appreciate advice being "dummed down" as much as possible. TIA

Reproducible Steps:

Followed the steps on the Get Started page EXACTLY

Current Output:

Error in compileCode(f, code, language = language, verbose = verbose) :
Compilation ERROR, function(s)/method(s) not created! In file included from C:/Users/schwa/Documents/R/win-library/3.6/BH/include/boost/random/detail/integer_log2.hpp:19:0,
from C:/Users/schwa/Documents/R/win-library/3.6/BH/include/boost/random/detail/int_float_pair.hpp:26,
from C:/Users/schwa/Documents/R/win-library/3.6/BH/include/boost/random/exponential_distribution.hpp:27,
from C:/Users/schwa/Documents/R/win-library/3.6/BH/include/boost/random/gamma_distribution.hpp:25,
from C:/Users/schwa/Documents/R/win-library/3.6/StanHeaders/include/stan/math/prim/mat/prob/dirichlet_rng.hpp:5,
from C:/Users/schwa/Documents/R/win-library/3.6/StanHeaders/include/stan/math/prim/mat.hpp:276,
from C:/Users/schwa/Documents/R/win-library/3.6/StanHeaders/include/stan/math/rev/mat.hpp:12,
from C:/Users/schwa/Documents/R/win-library/3.6/StanHeaders/include/stan/math.hpp:4,

Error in sink(type = "output") : invalid connection

Expected Output:

RStan Version:

The version of RStan you are running (e.g., from packageVersion("rstan"))

R Version:

2.18.12

Operating System:

Windows 10

Beginne damit, das Schulen-Beispiel von der RStan Get Started-Seite unter Windows 10 zu reproduzieren, und verwende dabei die angegebenen Versionen von R, RStan, Rtools und RStudio. Untersuche die Compiler-Ausgabe, die mit den Boost- und StanHeaders-Pfaden beginnt, und vergleiche anschließend das Ergebnis mit der dokumentierten Toolchain-Konfiguration. Als erledigt gilt die Aufgabe, wenn die Abweichung in der Umgebung oder der Kompilierungsfehler identifiziert und ein funktionierendes Beispiel bestätigt wurde.