my $upload_Handle = $q->upload($filename);
[download]

Looks like you're specifying a file name here.

It should be the name of the respective file input field in the form, presumably

<input type="file" name="upload_file" />
                         ^^^^^^^^^^^
[download]

just like you're already using it to get the file name via $q->param('upload_file').

my $filename   = $q->param('upload_file');    # returns (client-side) 
+name of the file
my $filehandle = $q->upload('upload_file');   # returns handle to the 
+server-side temp file
[download]