Error : Invalid multibyte character in parser at line~ - r

Question

I have a that working well in R ver 3.6.3.
And 1 Weeks ago I download R ver 4.0.0 because I replace my old computer with new one.
Then Suddenly my all code work very poor in R 4.0.0!
When I first search this error, most of people recommend some ways that is related to UTF-8
But What is very annoying is I'm already set my environment! Using Global option tap or else..
I tried to almost everything which is related UTF-8, but It never works.
Also, I tried to update packages tool already but again it never works.
Then Sometimes, I found somethings very strange by chance.
That is,
when I randomly push 'enter' key, suddenly the error didn't pop up!
But I can't find the exact reason why this was happened.
when I paste this code in R ver 3.6.3, It works very nicely! WHAT IS THE REASON!!!
This is same code but, when I tried to execute this code just changing the blank (I mean \r\n(?) \n(?) anyway..) Sometimes the code didn't work, Other times the code works.
This makes me crazy now I don't know the reason
Please help me
The code below is the code what I mentioned until now.
And I attached the picture that is the outcome in R ver 4.0.0
Thank you for reading.
Jeokhap <- function(target_pdf){
target <- target_pdf
page_jeok_1 <- grep("(4.{0,3}|라.{0,3})\\s{0,}이 (집합투자..|투자신탁)에 적합한 투자자 유형",target)
for (k in 1:(length(target)-page_jeok_1)){
if(length(grep("11.{0,3}매입,\\s{0,1}환매",target[(page_jeok_1+k)]))>0){
page_jeok_2 <- page_jeok_1+k
break
}
}
app_list_jeok=c()
for (k in page_jeok_2:page_jeok_1){
app_list_jeok <- append(target[k],app_list_jeok)
}
outcome_jeok <- paste(app_list_jeok,collapse="")
####extract sentence
check_jeok <- gregexpr("(4.{0,3}|라.{0,3})\\s{0,}이 (집합투자..|투자신탁)에 적합한 투자자 유형(.*?)11.{0,3}s{0,1}매입,\\s{0,1}환매",outcome_jeok)
sentence_choose_jeok3 <- regmatches(outcome_jeok,check_jeok)
if(length(regexpr("위험\\s{0,}\\등급\\s{0,}분류\\s{0,}기준",sentence_choose_jeok3))==1){
sentence_choose_jeok3 <- gsub("위험\\s{0,}\\등급\\s{0,}분류\\s{0,}기준.*","",sentence_choose_jeok3)
}else if(length(regexpr("위험\\s{0,}\\등급\\s{0,}분류\\s{0,}기준",sentence_choose_jeok3))>1){
sentence_choose_jeok3 <- sub("(위험\\s{0,}\\등급\\s{0,})(분류\\s{0,})(기준)","\\1\\2의 기준",sentence_choose_jeok3)
sentence_choose_jeok3 <- gsub("위험\\s{0,}\\등급\\s{0,}분류\\s{0,}기준.*","",sentence_choose_jeok3)
}
if(length(regexpr("투자\\s{0,}\\위험\\s{0,}등급\\s{0,}기준",sentence_choose_jeok3))==1){
sth1 <- gsub("투자\\s{0,}\\위험\\s{0,}등급\\s{0,}기준.*","",sentence_choose_jeok3)
}else if(length(regexpr("투자\\s{0,}\\위험\\s{0,}등급\\s{0,}기준",sentence_choose_jeok3))>1){
sentence_choose_jeok3 <- sub("(투자\\s{0,}\\위험\\s{0,})(등급\\s{0,})(기준)","\\1\\2의 기준",sentence_choose_jeok3)
sentence_choose_jeok3 <- gsub("투자\\s{0,}\\위험\\s{0,}등급\\s{0,}기준.*","",sentence_choose_jeok3)
}
return(1)
}