you can disable this warning by setting $CGI::LIST_CONTEXT_WARN to 0 or by using the multi_param() method instead

Nice to know, I wasn't aware of that change.

But: I would have expected a big fat warning (or at least a hint) right at the top of the documentation of CGI.pm. There is a warning that CGI.pm is no longer part of the Perl core, and another one deprecating HTML generating functions, but no obvious hint for experienced CGI.pm v3.x users. Sure, I could have read the Changes file, but I would expect API changes like this one to be announced in the main documentation.

To make things worse, the main documentation (still) has porting notes for the ancient cgi-lib.pl that hopefully nobody uses any more, but no notes for porting from the v3.x series to the v4.x series.

Alexander