Markdown error and warning in knitting out document

I am having issues running Rmarkdown and Project, and its associated output.

title: "Untitled"
author: "Oluwadare, Margaret"
date: "August 5, 2020"
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 <>.

When you click the **Knit** button a document will be generated that includes both contents 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}

## Including Plots

You can also embed plots, for example:

```{r pressure, echo=FALSE}

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

it gives me the following warning messages.

"C:/Users/HP/CONDA~1/envs/rstudio/Scripts/pandoc" +RTS -K512m -RTS --to html4 --from markdown+autolink_bare_uris+tex_math_single_backslash --output ERROR.html --email-obfuscation none --self-contained --standalone --section-divs --template "C:\Users\HP\OneDrive\Documents\R\win-library\4.0\rmarkdown\rmd\h\default.html" --no-highlight --variable highlightjs=1 --variable "theme:bootstrap" --include-in-header "C:\Users\HP\AppData\Local\Temp\Rtmpw9oVF0\rmarkdown-str340c1d5a1bbb.html" --mathjax --variable "mathjax-url:" --lua-filter "C:/Users/HP/OneDrive/Documents/R/win-library/4.0/rmarkdown/rmd/lua/pagebreak.lua" --lua-filter "C:/Users/HP/OneDrive/Documents/R/win-library/4.0/rmarkdown/rmd/lua/latex-div.lua" 
[WARNING] This document format requires a nonempty <title> element.
  Please specify either 'title' or 'pagetitle' in the metadata.
  Falling back to 'ERROR.utf8'

Also when I tried to use reprex() to report the above issues I got an error message as follows:

Rendering reprex...
Error: callr subprocess failed: <text>:18:68: unexpected symbol
17: #+ reprex-body
18: "C:/Users/HP/CONDA~1/envs/rstudio/Scripts/pandoc" +RTS -K512m -RTS
Type .Last.error.trace to see where the error occured


This challenge has been on since I updated R, Rstudio, and all the packages. I had to do package update to be sure the packages on my Rstudio are not outdated. But still, the challenge persists. Below are my session information and version details:

R version 4.0.2 (2020-06-22)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows >= 8 x64 (build 9200)

Matrix products: default

[1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United States.1252
[3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C
[5] LC_TIME=English_United States.1252

attached base packages:
[1] stats graphics grDevices utils datasets methods base

other attached packages:
[1] reprex_0.3.0 shiny_1.5.0 acs_2.1.4 XML_3.99-0.5 stringr_1.4.0
[6] ggrepel_0.8.2 R.utils_2.9.2 R.oo_1.23.0 R.methodsS3_1.8.0 data.table_1.13.0
[11] ggplot2_3.3.2 dplyr_1.0.1 xtable_1.8-4 quantmod_0.4.17 TTR_0.23-6
[16] xts_0.12-0 zoo_1.8-8 lubridate_1.7.9

loaded via a namespace (and not attached):
[1] httr_1.4.2 pkgload_1.1.0 jsonlite_1.7.0 splines_4.0.2
[5] Formula_1.2-3 assertthat_0.2.1 latticeExtra_0.6-29 remotes_2.2.0
[9] yaml_2.2.1 sessioninfo_1.1.1 pillar_1.4.6 backports_1.1.7
[13] lattice_0.20-41 glue_1.4.1 digest_0.6.25 RColorBrewer_1.1-2
[17] promises_1.1.1 checkmate_2.0.0 colorspace_1.4-1 htmltools_0.5.0
[21] httpuv_1.5.4 Matrix_1.2-18 plyr_1.8.6 clipr_0.7.0
[25] pkgconfig_2.0.3 devtools_2.3.1 purrr_0.3.4 scales_1.1.1
[29] processx_3.4.3 whisker_0.4 jpeg_0.1-8.1 later_1.1.0.1
[33] tibble_3.0.3 generics_0.0.2 usethis_1.6.1 ellipsis_0.3.1
[37] withr_2.2.0 nnet_7.3-14 cli_2.0.2 survival_3.1-12
[41] magrittr_1.5 crayon_1.3.4 mime_0.9 ps_1.3.3
[45] memoise_1.1.0 evaluate_0.14 fansi_0.4.1 fs_1.5.0
[49] foreign_0.8-80 pkgbuild_1.1.0 prettyunits_1.1.1 rsconnect_0.8.16
[53] tools_4.0.2 lifecycle_0.2.0 munsell_0.5.0 cluster_2.1.0
[57] callr_3.4.3 compiler_4.0.2 rlang_0.4.7 grid_4.0.2
[61] rstudioapi_0.11 miniUI_0.1.1.1 base64enc_0.1-3 rmarkdown_2.3
[65] testthat_2.3.2 gtable_0.3.0 curl_4.3 R6_2.4.1
[69] gridExtra_2.3 knitr_1.29 fastmap_1.0.1 rprojroot_1.3-2
[73] desc_1.2.0 stringi_1.4.6 Rcpp_1.0.5 vctrs_0.3.2
[77] rpart_4.1-15 acepack_1.4.1 png_0.1-7 tidyselect_1.1.0
[81] xfun_0.16

platform x86_64-w64-mingw32
arch x86_64
os mingw32
system x86_64, mingw32
major 4
minor 0.2
year 2020
month 06
day 22
svn rev 78730
language R
version.string R version 4.0.2 (2020-06-22)
nickname Taking Off Again

Based on the example given, it's not totally clear to me what is in your R Markdown doc and what isn't, but it appears that there's a call to reprex() in the doc.

I don't think reprex() is intended for an R Markdown doc.

When I tried adding a simple one, I wasn't able to replicate your error message, but my R Markdown doc didn't fully knit.

That all being said, is there a backtick/gravemark (this thing -> "`'")
at the top of your YAML header?

When I add that before the topmost --- I am able to replicate the [WARNING] This document format requires a nonempty <title> element. message.
I'd remove that and retry.


I tried to use replex() so i can post the sample code here but the replex() command produced and error message instage. Also the back tic (`) was to make my code reproducible here, i guess it didn't come out clean as it should.

I want to make an Rmarkdown doc but it keeps giving me the warning as described in my post and then produce a blank html or pdf document.