Sounds like $q->uploadInfo($fileName) is returning "undef" rather than the expected hash reference. Given that you've already extracted that value into $fileInfo a few lines earlier, it might make sense to check that you've got what you hope you've got (i.e. a hash reference) before going ahead and trying to dereference it. I've always thought that the example in the CGI.pm docs that calls uploadInfo and just assumes that it works seemed a bit reckless, so I've always done that in two stages.

All of which leaves you having to work out why you're getting "undef" rather than a useful value. Without seeing more of your code it's hard to be much help, but one idea springs to mind. It looks a bit unusual creating a CGI object in your fileUpload subroutine. Usually, you'd do that at the start at the CGI program and just pass that object around. Are you also creating a CGI object elsewhere in your program? You can only create one CGI object from each HTTP request. If you try to create a second one then all of its attributes will be undefined. Is that what has happened here?