CPANTS

Plack-Middleware-RequestHeaders 0.01

This is not the latest release. The following issues may have already been fixed in the newer releases.

has_meta_yml: Add a META.yml to the distribution. Your buildtool should be able to autogenerate it.
no_broken_module_install: Upgrade the bundled version of Module::Install to the most current release. Alternatively, you can switch to another build system / installer that does not suffer from this problem. (ExtUtils::MakeMaker, Module::Build both of which have their own set of problems.)
has_human_readable_license: Add a section called "LICENSE" to the documentation, or add a file named LICENSE to the distribution.
has_license_in_source_file: Add =head1 LICENSE and the text of the license to the main module in your code.

has_meta_json: Add a META.json to the distribution. Your buildtool should be able to autogenerate it.
meta_yml_has_license: Define the license if you are using in Build.PL. If you are using MakeMaker (Makefile.PL) you should upgrade to ExtUtils::MakeMaker version 6.31.
has_known_license_in_source_file: Add =head1 LICENSE and/or the proper text of the well-known license to the main module in your code.

This is not a critical issue. Currently mainly informative for the CPANTS authors. It might be removed later.

List all modules used in the Makefile.PL/Build.PL in META.yml configure_requires

Error:

Name	Abstract	Version	View
Plack::Middleware::RequestHeaders	modify HTTP request headers	0.01	metacpan