Good advice. I'd include the paths too as the longer they are the more likely it is that one of them may have a typo.

copy( $source, $target ) or die "couldn't copy file '$source' to '$tar
+get': $!";
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the other files in that folder are copied but not this, if I reduce the name of the file then it works but that is not possible for me.

SSCCE works for me.

use strict;
use warnings;

use File::Copy 'copy';
use Test::More tests => 1;

my $longname = 'foo_' . ('z' x 200);
open my $fh, '>', $longname;
print $fh "Hello!\n";
close $fh;

my $toname = 'bar_' . ('z' x 200);
ok copy ($longname, $toname) or diag $!;
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Maybe your O/S or your filesystem is the problem here?

"could not do at C:\sandboxes\Scripts\dummy.pl line 9" the error I got. any other solution? or can I copy the folders, sub folders and files in line of code? I'm using Windows

Which version of Windows? It doesn't look like you tried what I suggested, note the $!

copy( $source, $target ) or die "couldn't copy file $!";

#---------------------------------------------------^
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The error is "couldn't copy file No such file or directory at C:\sandboxes\Scripts\dummy.pl line 9."

Windows 10 and the file is present because there are other files which I copy in that directory