Error in compileCode(f, code, language = language, verbose = verbose) : Compilation ERROR, function(s)/method(s) not created! Again

@bgoodri - Thank you for all of your help. I have run into the same issues, and I have tried the fixes proposed in this thread as well as the suggested steps in a related thread (Not able to run Eight Schools example on rstan 2.21.1 & StanHeaders 2.21.0-5) with no luck.

I tried running:

install.packages(
    "https://win-builder.r-project.org/8bPDZPDG0522/rstan_2.21.2.zip",
    repos = NULL, type = "win.binary")

But got the error message:

Warning in install.packages :
  cannot open URL 'https://win-builder.r-project.org/8bPDZPDG0522/rstan_2.21.2.zip': HTTP status was '404 Not Found'
Error in download.file(p, destfile, method, mode = "wb", ...) : 
  cannot open URL 'https://win-builder.r-project.org/8bPDZPDG0522/rstan_2.21.2.zip'

Did the ZIP file get removed?

My session info:

R version 4.0.2 (2020-06-22)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 18362)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252   
[3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

loaded via a namespace (and not attached):
 [1] compiler_4.0.2  htmltools_0.4.0 tools_4.0.2     yaml_2.2.1      Rcpp_1.0.4.6    rmarkdown_2.3  
 [7] knitr_1.28      xfun_0.14       digest_0.6.25   packrat_0.5.0   rlang_0.4.6     evaluate_0.14