When trying to cpan > upgrade File::Slurp 9999.27 on Windows 10, Strawberry Perl 5.26, I receive the following error: t/tainted.t ................... can't write to '\tempe8UUZ': Permission denied at t/tainted.t line 26. # Looks like your test exited with 13 before it could output anything. t/tainted.t ................... Dubious, test returned 13 (wstat 3328, 0xd00) Failed 9/9 subtests tainted's line 22 is my $path = temp_file_path(); which is the $path used in line 26 open(my $fh, ">", $path) or die "can't write to '$path': $!"; In turn, temp_file_path appears to come from FileSlurpTest (line 17) use FileSlurpTest qw(temp_file_path trap_function trap_function_list_context); but I can't find where FileSlurpTest is coming from. Anyway, a temporary path such as \tempe8UUZ\ is apparently unwritable on Windows. Perhaps it should be created under .\?