Sweave Error in compiling simple helloworld pdf - rstudio

Question

Using RStudio, Sweave, R 3.5.1, and MikTex 2.9... I've run out of things I can think to check. Any help would be greatly appreciated!
\documentclass{article}
\begin{document}
\SweaveOpts{concordance=TRUE}
Hello World!
\end{document}
Error Message:
C:/PROGRA~1/MIKTEX~1.9/miktex/bin/pdflatex.exe (exit code 1)
First, I checked the sweave options to make sure ``Enable shell escape commands" was not checked. Didn't work.
I noticed two entries for the MikTeX installation. I removed it from user variables and kept it in the system variables (through the environment variables menu in Windows).
> Sys.getenv("PATH")
[1] "C:\\Program Files\\R\\R-3.5.1\\bin\\x64;C:\\ProgramData\\Oracle\\Java\\javapath;C:\\Python36\\;C:\\Python36\\Scripts\\;C:\\Program Files\\Dell\\DW WLAN Card;C:\\Program Files (x86)\\Intel\\iCLS Client\\;C:\\Program Files\\Intel\\iCLS Client\\;C:\\WINDOWS\\system32;C:\\WINDOWS;C:\\WINDOWS\\System32\\Wbem;C:\\WINDOWS\\System32\\WindowsPowerShell\\v1.0\\;C:\\Program Files (x86)\\Intel\\Intel(R) Management Engine Components\\DAL;C:\\Program Files\\Intel\\Intel(R) Management Engine Components\\DAL;C:\\Program Files (x86)\\Intel\\Intel(R) Management Engine Components\\IPT;C:\\Program Files\\Intel\\Intel(R) Management Engine Components\\IPT;c:\\Program Files\\WIDCOMM\\Bluetooth Software\\;c:\\Program Files\\WIDCOMM\\Bluetooth Software\\syswow64;C:\\Program Files\\MiKTeX 2.9\\miktex\\bin\\x64\\;C:\\WINDOWS\\System32\\OpenSSH\\;C:\\Program Files\\Java\\jdk-9.0.4\\bin;C:\\Tcl\\bin;C:\\Users\\usr2\\AppData\\Local\\Microsoft\\WindowsApps;C:\\Program Files (x86)\\Google\\Chrome\\Application;C:\\ProgramData\\Oracle\\Java\\javapath;C:\\Python36\\;C:\\Python36\\Scripts\\;C:\\Program Files\\Dell\\DW WLAN Card;C:\\Program Files (x86)\\Intel\\iCLS Client\\;C:\\Program Files\\Intel\\iCLS Client\\;C:\\WINDOWS\\system32;C:\\WINDOWS;C:\\WINDOWS\\System32\\Wbem;C:\\WINDOWS\\System32\\WindowsPowerShell\\v1.0\\;C:\\Program Files (x86)\\Intel\\Intel(R) Management Engine Components\\DAL;C:\\Program Files\\Intel\\Intel(R) Management Engine Components\\DAL;C:\\Program Files (x86)\\Intel\\Intel(R) Management Engine Components\\IPT;C:\\Program Files\\Intel\\Intel(R) Management Engine Components\\IPT;c:\\Program Files\\WIDCOMM\\Bluetooth Software\\;c:\\Program Files\\WIDCOMM\\Bluetooth Software\\syswow64;C:\\Program Files\\MiKTeX 2.9\\miktex\\bin\\x64\\;C:\\WINDOWS\\System32\\OpenSSH\\;C:\\Program Files\\Java\\jdk-9.0.4\\bin;C:\\Tcl\\bin;C:\\Users\\usr2\\AppData\\Local\\Microsoft\\WindowsApps;C:\\ProgramData\\Oracle\\Java\\javapath;C:\\Python36\\;C:\\P"
And after removing one of them
> Sys.getenv("PATH")
[1] "C:\\Program Files\\R\\R-3.5.1\\bin\\x64;C:\\ProgramData\\Oracle\\Java\\javapath;C:\\Python36\\;C:\\Python36\\Scripts\\;C:\\Program Files\\Dell\\DW WLAN Card;C:\\Program Files (x86)\\Intel\\iCLS Client\\;C:\\Program Files\\Intel\\iCLS Client\\;C:\\WINDOWS\\system32;C:\\WINDOWS;C:\\WINDOWS\\System32\\Wbem;C:\\WINDOWS\\System32\\WindowsPowerShell\\v1.0\\;C:\\Program Files (x86)\\Intel\\Intel(R) Management Engine Components\\DAL;C:\\Program Files\\Intel\\Intel(R) Management Engine Components\\DAL;C:\\Program Files (x86)\\Intel\\Intel(R) Management Engine Components\\IPT;C:\\Program Files\\Intel\\Intel(R) Management Engine Components\\IPT;c:\\Program Files\\WIDCOMM\\Bluetooth Software\\;c:\\Program Files\\WIDCOMM\\Bluetooth Software\\syswow64;C:\\Program Files\\MiKTeX 2.9\\miktex\\bin\\x64\\;C:\\WINDOWS\\System32\\OpenSSH\\;C:\\Program Files\\Java\\jdk-9.0.4\\bin;C:\\Tcl\\bin;C:\\Users\\pbake\\AppData\\Local\\Microsoft\\WindowsApps;C:\\Program Files (x86)\\Google\\Chrome\\Application;C:\\ProgramData\\Oracle\\Java\\javapath;C:\\Python36\\;C:\\Python36\\Scripts\\;C:\\Program Files\\Dell\\DW WLAN Card;C:\\Program Files (x86)\\Intel\\iCLS Client\\;C:\\Program Files\\Intel\\iCLS Client\\;C:\\WINDOWS\\system32;C:\\WINDOWS;C:\\WINDOWS\\System32\\Wbem;C:\\WINDOWS\\System32\\WindowsPowerShell\\v1.0\\;C:\\Program Files (x86)\\Intel\\Intel(R) Management Engine Components\\DAL;C:\\Program Files\\Intel\\Intel(R) Management Engine Components\\DAL;C:\\Program Files (x86)\\Intel\\Intel(R) Management Engine Components\\IPT;C:\\Program Files\\Intel\\Intel(R) Management Engine Components\\IPT;c:\\Program Files\\WIDCOMM\\Bluetooth Software\\;c:\\Program Files\\WIDCOMM\\Bluetooth Software\\syswow64;C:\\WINDOWS\\System32\\OpenSSH\\;C:\\Program Files\\Java\\jdk-9.0.4\\bin;C:\\Tcl\\bin;C:\\Users\\pbake\\AppData\\Local\\Microsoft\\WindowsApps;C:\\ProgramData\\Oracle\\Java\\javapath;C:\\Python36\\;C:\\P;"
Didn't work.
Also,
> Sys.which("pdflatex")
"C:\\PROGRA~1\\MIKTEX~1.9\\miktex\\bin\\x64\\pdflatex.exe"
> Sys.getenv("R_ENVIRON")
[1] ""
Here is the contents of the .log file created, but I don't see any hints toward solving this issue.
This is pdfTeX, Version 3.14159265-2.6-1.40.18 (MiKTeX 2.9.6500 64-bit) (preloaded format=pdflatex 2018.1.26) 5 SEP 2018 20:49
entering extended mode
**./helloworld.tex
(helloworld.tex
LaTeX2e <2017-04-15>
Babel <3.15> and hyphenation patterns for 75 language(s) loaded.
("C:\Users\usr2\AppData\Local\Programs\MiKTeX 2.9\tex\latex\base\article.cls"
Document Class: article 2014/09/29 v1.4h Standard LaTeX document class
("C:\Users\usr2\AppData\Local\Programs\MiKTeX 2.9\tex\latex\base\size10.clo"
File: size10.clo 2014/09/29 v1.4h Standard LaTeX file (size option)
)
\c#part=\count79
\c#section=\count80
\c#subsection=\count81
\c#subsubsection=\count82
\c#paragraph=\count83
\c#subparagraph=\count84
\c#figure=\count85
\c#table=\count86
\abovecaptionskip=\skip41
\belowcaptionskip=\skip42
\bibindent=\dimen102
) (C:/PROGRA~1/R/R-35~1.1/share/texmf/tex/latex\Sweave.sty
Package: Sweave
("C:\Users\usr2\AppData\Local\Programs\MiKTeX 2.9\tex\latex\base\ifthen.sty"
Package: ifthen 2014/09/29 v1.1c Standard LaTeX ifthen package (DPC)
)
("C:\Users\usr2\AppData\Local\Programs\MiKTeX 2.9\tex\latex\graphics\graphicx.
sty"
Package: graphicx 2017/06/01 v1.1a Enhanced LaTeX Graphics (DPC,SPQR)
("C:\Users\usr2\AppData\Local\Programs\MiKTeX 2.9\tex\latex\graphics\keyval.st
y"
Package: keyval 2014/10/28 v1.15 key=value parser (DPC)
\KV#toks#=\toks14
)
("C:\Users\usr2\AppData\Local\Programs\MiKTeX 2.9\tex\latex\graphics\graphics.
sty"
Package: graphics 2017/06/25 v1.2c Standard LaTeX Graphics (DPC,SPQR)
("C:\Users\usr2\AppData\Local\Programs\MiKTeX 2.9\tex\latex\graphics\trig.sty"
Package: trig 2016/01/03 v1.10 sin cos tan (DPC)
)
("C:\Users\usr2\AppData\Local\Programs\MiKTeX 2.9\tex\latex\graphics-cfg\graph
ics.cfg"
File: graphics.cfg 2016/06/04 v1.11 sample graphics configuration
)
Package graphics Info: Driver file: pdftex.def on input line 99.
("C:\Users\usr2\AppData\Local\Programs\MiKTeX 2.9\tex\latex\graphics-def\pdfte
x.def"
File: pdftex.def 2018/01/08 v1.0l Graphics/color driver for pdftex
))
\Gin#req#height=\dimen103
\Gin#req#width=\dimen104
)

Answer 1

Removing the two TeX paths from the environment variables wasn't enough. It appears there were two different TeX installations. Removing and installing a fresh LaTeX distribution worked!