Knit error in RStudio: pandoc conversion failed with error 23. Extension ascii_identifiers is not supported for markdown

Question

Trying to knit a doc into html, RStudio would hang on the conversion to html part. I looked around and it looked like this happened to other folks when they were using an out of date pandoc version. I updated pandoc to 2.8. I received the error in the title. Looking around again, it appeared that v 2.5 seemed stable. I installed that, restarted my computer, and still get the same error.

repex is the default example when you create an RMarkdown file in RStudio: file -> New file -> R Markdown -> html.

---
title: "repexpandocerror23"
author: "Adam Korejwa"
date: "11/22/2019"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```

## R Markdown

This is an R Markdown document. Markdown is a simple formatting syntax for 
authoring HTML, PDF, and MS Word documents. For more details on using R 
Markdown see <http://rmarkdown.rstudio.com>.

When you click the **Knit** button a document will be generated that 
includes both content as well as the output of any embedded R code chunks 
within the document. You can embed an R code chunk like this:

```{r cars}
summary(cars)
```

## Including Plots

You can also embed plots, for example:

```{r pressure, echo=FALSE}
plot(pressure)
```

Note that the `echo = FALSE` parameter was added to the code chunk to 
prevent printing of the R code that generated the plot.

Answer 1

I have fixed this issue two months ago. Please make sure your rmarkdown version is at least v1.16. Once again, when in doubt, consider updating your packages:

update.packages(ask = FALSE, checkBuilt = TRUE)