title: Error in loadnamespace when knitting R_markdown to PDF
body: <p>This is the first time I use R_Markdown</p>
  <p>I created a new R_Markdown and am trying to knit it to PDF. When I do it I get the following error</p>
  <pre><code>
  processing file: R_markdown.Rmd
    |..........                                                            |  14%
    ordinary text without R code
  
    |....................                                                  |  29%
  label: setup (with options) 
  List of 1
   $ include: logi FALSE
  
    |..............................                                        |  43%
    ordinary text without R code
  
    |........................................                              |  57%
  label: cars
    |..................................................                    |  71%
    ordinary text without R code
  
    |............................................................          |  86%
  label: pressure (with options) 
  List of 1
   $ echo: logi FALSE
  
    |......................................................................| 100%
    ordinary text without R code
  
  
  output file: R_markdown.knit.md
  
  &quot;C:/Program Files/RStudio/bin/pandoc/pandoc&quot; +RTS -K512m -RTS R_markdown.utf8.md --to latex --from markdown+autolink_bare_uris+tex_math_single_backslash --output R_markdown.tex --lua-filter &quot;C:\Users\faiel\Documents\R\win-library\4.0\rmarkdown\rmarkdown\lua\pagebreak.lua&quot; --lua-filter &quot;C:\Users\faiel\Documents\R\win-library\4.0\rmarkdown\rmarkdown\lua\latex-div.lua&quot; --self-contained --highlight-style tango --pdf-engine pdflatex --variable graphics --variable &quot;geometry:margin=1in&quot; 
  Error in loadNamespace(j &lt;- i[[1L]], c(lib.loc, .libPaths()), versionCheck = vI[[j]]) : 
    namespace 'xfun' 0.17 is already loaded, but &gt;= 0.19 is required
  Calls: &lt;Anonymous&gt; ... namespaceImportFrom -&gt; asNamespace -&gt; loadNamespace
  Execution halted
  
  </code></pre>
  <p>I can't understand why this is happening. I tried the following</p>
  <pre><code>install.packages(&quot;rmarkdown&quot;)
  </code></pre>
  <p>and</p>
  <pre><code>update.packages(ask = FALSE, checkBuilt = TRUE)
  tinytex::tlmgr_update()
  </code></pre>
  <p>But without any luck</p>