I tried everything! I tried resetting the CRAN mirror, uninstalling and then installing R, doing the same with all my packages in RStudio, hashtagging out the packages in RStudio...I have to knit a file to html and I am getting this message: (also, I tried testing another of my .rmd files in RStudio and even though in the past I could knit that one, I received this same error message)
Error in contrib.url(repos, "source") : Trying to use CRAN without setting a mirror
Call: ...withVisible -> eval -> eval -> install.packages -> contrib.url
Execution halted