Please provide a fully self-contained code sample that includes its own small sample data-set, that will compile and run, and that will demonstrate the behavior you are describing. It should be possible to demonstrate both examples.

If you add use diagnostics; to your script you will get a more thorough explanation of what is meant by each of the error messages. As I glanced over perldiag, I saw this:

Can't use a hash as a reference

(F) You tried to use a hash as a reference, as in %foo->{"bar"} or %$r
+ef->{"hello"} . Versions of perl <= 5.22.0 used to allow this syntax,
+ but shouldn't have. This was deprecated in perl 5.6.1.
[download]

That is probably a good explanation of what you are seeing in that second error message.