Unbelievable error ..

Quite so - it is indeed very hard to believe. Your code as posted works fine:

$ cat 11149222.pl
#!/usr/bin/perl
use strict;
use warnings;
 
print "Content-type: text/html\n\n";
 
print "Hello World!";

$ perl 11149222.pl
Content-type: text/html

Hello World!$ perl -v | head -3

This is perl 5, version 34, subversion 0 (v5.34.0) built for x86_64-li
+nux-thread-multi

$
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Here the code snippet I do do now

#!c:/xampp/perl/bin/perl.exe
use warnings;
use CGI;
use Time::HiRes qw(gettimeofday);
my $query = CGI->new;
my $dir = "C:/Users/41786/OneDrive/Documents/recordz1/";
print $query->header; 

test();
 
sub test {
    open (FILE, "<$dir/test2.html") or die "cannot open file $dir/test
+2.html";
    my $content = "";
    my $string .= "<a href=\"/cgi-bin/recordz.cgi?lang=FR&amp;session=
+1&page=historique&amp;article=1amp;min_index=1&amp;max_index=40\" ><-
+1-></a>&#160;&nbsp;";        
    while (<FILE>) {    
        s/\$ARTICLE{'index'}/$string/g;
        $content .= $_;    
    }
    print "Content-Type: text/html\n\n"; 
    print $content;
    close (FILE);
}
[download]

Use three argument open, http://modernperlbooks.com/mt/2010/04/three-arg-open-migrating-to-modern-perl.html, use $! when calling die to tell you why the open failed.

You didn't mention what operating system and which Perl version you use, which makes it difficult to help.

#!c:/xampp/perl/bin/perl.exe
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