my @last_lines;
while (<>) {
   if ($_ eq "D : Error Occurred\n") {
      print @last_lines,$_;
      last;
   }
   push @last_lines,$_; 
   shift @last_lines if @last_lines > 4;
}
[download]

If you really only need the first 2 lines after the last "====" line, then maybe this is a good start:

my @last_lines;
while (<>) {
   if ($_ eq "D : Error Occurred\n") {
      print @last_lines,$_;
      last;
   }
   if (/===/) {
      @last_lines =();
   }
   elsif (@last_lines < 2) {
      push @last_lines,$_;
   }
}
[download]