In my experience, such an error indicates that one opened a file for writing but one did not check if that open() was successful. Then one tried to print to the filehandle (of the unopened file) none-the-less, and, understandably, one got an error message.

What's at B:/PortableApps/CitrusPerl/perl/lib/IO/Handle.pm line 417? cpan.org's IO::Handle, line 417 is my $this = shift;.