Not a GLOB reference

Not a GLOB reference

(F) Perl was trying to evaluate a reference to a "typeglob" (that is, a symbol table entry that looks like *foo) but found a reference to something else instead. You can use the ref function to find out what kind of ref it really was.

typeglob

Use of  a single identifier, prefixed with *. For example, *name stands for any or all of $name, @name, %name, &name, or just name. How you use it determines whether it is interpreted as all or only one of them. See "Typeglobs and Filehandles" in Chapter 2.

$fh = *STDOUT;
$fh = \*STDOUT;