Mojo::Transaction::success is DEPRECATED in favor of Mojo::Transaction::result and Mojo::Transaction::error at C:/strawberry/perl/site/lib/Mojolicious/Plugin/ReCAPTCHAv2.pm line 100.
Error code : missing-input-response

##</code><code>##

%= form_for surv => (method => 'POST') => begin
<ul class='form-style-1'>
<li>
%= label_for name => 'Full name:'
%= text_field 'firstname',  class=> 'field-divided', placeholder=>'First'
%= text_field 'name',  class=> 'field-divided', placeholder=>'Last'
.....
%= label_for lang2 => 'Skill in a second national language:'
%= select_field lang2 => [[Small => 'small'], [Standard => 'standard'], [Good => 'good', selected => 'selected']], class => 'field-select'
</li>
<li>
<%= $captcha %>
</li>
<li>
%= input_tag Send => 'Send', type => 'submit'
</li>
</ul>
%end

##</code><code>##

....
use Mojolicious::Plugin::ReCAPTCHAv2;

sub startup {
....
 $self->plugin('ReCAPTCHAv2', {
        sitekey       => '...',                
        secret        =>  '....',      
    });
...

}

##</code><code>##

sub post {
    my $c   = shift;
    my $app = $c->app;
    if ( $app->recaptcha_verify ) {
        my $p = $c->req->body_params->to_hash;
        #... test for missing data
	#build sql string and add the data
            $app->log->debug($sql);
            my $stm = $app->db1->prepare($sql) or die $app->db1->errstr;
            $stm->execute() or die $stm->errstr;
            $app->stash( msg => "Data well received, thank you" );
        }

    }
    else {
        if ( my $err = $app->recaptcha_get_errors ) {
            foreach my $e ( @{$err} ) {
                $app->log->debug( "Error code : " . $e );
            }
        }
        else {
            $app->log->debug("Surv.pm: could be a bot here");
        }

    }

}

##</code><code>##

	my %verify_params = (
				remoteip => $c->tx->remote_address,
				response => ( $c->req->param('g-recaptcha-response') || '' ),
				secret   => $plugin->conf->{'secret'},
			);

##</code><code>##

use Mojolicious::Lite;
use DBI;
use Mojolicious::Plugin::ReCAPTCHAv2;

plugin 'ReCAPTCHAv2' => {
    sitekey     => '... your value received from google',
    secret      => '... idem',
    api_timeout => 120,
};

get '/surv' => sub {
    my $c = shift;
    $c->stash( captcha => $c->app->recaptcha_get_html );
};

post '/surv' => sub {
    my $c   = shift;
    my $app = $c->app;

    if ( $app->recaptcha_verify ) {
        $app->log->debug( "Hi there " . $c->param('first name') );
    }
    else {
        if ( my $err = $app->recaptcha_get_errors ) {
            foreach my $e ( @{$err} ) {
                $app->log->debug( "Error code : " . $e );
            }
        }
        else {
            $app->log->debug("could be a bot here");
        }

    }

};

app->start;
__DATA__
@@ surv.html.ep
%= form_for surv => (method => 'POST') => begin
%= text_field 'first_name'
<%= $captcha %>
%= submit_button
%en

##</code><code>##

{
    hypnotoad => {
      listen => ['https://*:3000']
                 }
}