R Markdown failed to render PDF and render .tex instead

Question

I have been using RMarkdown via R Studio to render PDF for a while but suddenly it failed to render PDF with the following error. Instead of PDF, it render a .tex file which I'm unsure why.

"C:/Program Files/RStudio/bin/pandoc/pandoc" +RTS -K512m -RTS Question-10.2-and-3---RMD --to latex --from markdown+autolink_bare_uris+tex_math_single_backslash --output Question-10.2-and-3---RMD.tex --lua-filter "C:\Users\hangt\OneDrive\Documents\R\win-library\4.1\rmarkdown\rmarkdown\lua\pagebreak.lua" --lua-filter "C:\Users\hangt\OneDrive\Documents\R\win-library\4.1\rmarkdown\rmarkdown\lua\latex-div.lua" --self-contained --highlight-style tango --pdf-engine pdflatex --variable graphics --variable "geometry:margin=1in" 
! Package inputenc Error: Unicode character € (U+0080)
(inputenc)                not set up for use with LaTeX.

Try other LaTeX engines instead (e.g., xelatex) if you are using pdflatex. See https://bookdown.org/yihui/rmarkdown-cookbook/latex-unicode.html
Error: LaTeX failed to compile Question-10.2-and-3---RMD.tex. See https://yihui.org/tinytex/r/#debugging for debugging tips. See Question-10.2-and-3---RMD.log for more info.
Execution halted

Sorry if the way I describe the issue is vague.

Thanks.

Answer 1

Welcome to TeX.SE. Your document has a Euro symbol, which can not be compiled by pdflatex. There are several possible ways to fix this. Assuming you are writing an Rmarkdown document, you can add any one of these to the document header:

1. \usepackage{eurosym}
2. \usepackage{textcomp}
3. \DeclareUnicodeCharacter{20AC}{\euro}

Alternatively, you can compile your .Rmd file with xelatex in RStudio by going to Tools > Global Options > Sweave and in Typeset LaTeX into PDF using: choose XeLaTeX.

Here is a MWE that uses the eurosym package, which can be compiled with pdflatex.

---
title: "TeX.SE"
output: pdf_document
header-includes: 
  - \usepackage{eurosym}
---

The book is 10 \euro.

The book is \euro 10.

The book is \EUR{10}.