int10h@maxwell ~/Desktop/mwe $ pdflatex mwe.tex 
This is pdfTeX, Version 3.14159265-2.6-1.40.18 (TeX Live 2017) (preloaded format=pdflatex)
 restricted \write18 enabled.
entering extended mode
(./mwe.tex
LaTeX2e <2017/01/01> patch level 3
Babel <3.10> and hyphenation patterns for 10 language(s) loaded.
(/usr/share/texmf-dist/tex/latex/base/article.cls
Document Class: article 2014/09/29 v1.4h Standard LaTeX document class
(/usr/share/texmf-dist/tex/latex/base/size10.clo))
(/usr/share/texmf-dist/tex/generic/babel/babel.sty

! Package babel Error: Unknown option `UKenglish'. Either you misspelled it
(babel)                or the language definition file UKenglish.ldf was not fo
und.

See the babel package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              
                                                  
l.393 \ProcessOptions*
                      
? 
! Emergency stop.
 ...                                              
                                                  
l.393 \ProcessOptions*
                      
!  ==> Fatal error occurred, no output PDF file produced!
Transcript written on mwe.log.
int10h@maxwell ~/Desktop/mwe $