There are a number of useful Perl scripts distributed with TeX and friends. Perl deprecated the use of unescaped literal characters in regular expressions in version 5.16 and now they're no longer permissible and will cause an error. Some of the Perl scripts in the TeX distributions suffered from this problem in the past but have now been fixed, but users are still picking up old versions that don't work with new versions of Perl.
Can we have a definitive list of all Perl scripts provided with TeX distributions that have fixed this issue (with version number) for easy reference whenever there's a new question that includes an error message like:
Unescaped left brace in regex is illegal here in regex; marked by <-- HERE