Hi Everyone, I have the same problem with markdown not knitting to html, this has happened all of a sudden and I can not put my finger on anything that could have triggered the problem (up until then all my markdowns were knitting correctly). I have bypassed the error by downloading pandoc on the command line using homebrew. I can now produce a html document by typing
library(rmarkdown)
rmarkdown::render("file.Rmd", "html_document")
Please let me know if you know a better solution.