Mm, no sorry, I do not know why you refer to MyApp. My application is Myapp. I am on linux which is case sensitive. Sorry, my problem is not so simple...

Can you guess why I refer to MyApp?

That is the default name for a new app -- thats me trying to complete/reproduce the problem, trying to do step 1 for you ( make it short and reproducible )

#!/usr/bin/perl --
use Mojolicious::Lite;

app->routes->under(sub{
    my( $c ) = @_;
    return defined($c->session('userid')) 
})->get ( '/breaky' => 'index' );

app->routes->under(sub{
    my( $c ) = @_;
    return defined($c->session('userid')) 
})->name('achey')->get ( '/breakyname' => 'index' );

# Authenticate based on name parameter
under sub {
    my $c = shift;
    
    # Authenticated
    my $name = $c->param('name') || '';
    return 1 if $name eq 'Bender';
    # Not authenticated
    $c->render(template => 'denied');
    return undef;
};

# Only reached when authenticated
get '/' => 'index';

app->start;
__DATA__

@@ denied.html.ep
You are not Bender, permission denied.

@@ index.html.ep
Hi Bender.
[download]

$ perl mojo-under-breaky.pl get /
[Wed Nov 25 14:53:52 2015] [debug] GET "/"
[Wed Nov 25 14:53:52 2015] [debug] Routing to a callback
[Wed Nov 25 14:53:52 2015] [debug] Rendering template "denied.html.ep"
+ from DATA section
[Wed Nov 25 14:53:52 2015] [debug] 200 OK (0.004443s, 225.073/s)
You are not Bender, permission denied.

$ perl mojo-under-breaky.pl get /?name=Bender
[Wed Nov 25 14:54:17 2015] [debug] GET "/"
[Wed Nov 25 14:54:17 2015] [debug] Routing to a callback
[Wed Nov 25 14:54:17 2015] [debug] Rendering template "index.html.ep" 
+from DATA section
[Wed Nov 25 14:54:17 2015] [debug] 200 OK (0.004540s, 220.264/s)
Hi Bender.

$ perl mojo-under-breaky.pl get /breaky
[Wed Nov 25 14:55:33 2015] [debug] GET "/breaky"
[Wed Nov 25 14:55:33 2015] [debug] Routing to a callback
[Wed Nov 25 14:55:33 2015] [debug] Your secret passphrase needs to be 
+changed
[Wed Nov 25 14:55:33 2015] [debug] Nothing has been rendered, expectin
+g delayed response
[Wed Nov 25 14:55:48 2015] [debug] Inactivity timeout
Problem loading URL "http://127.0.0.1:2556/breaky": Premature connecti
+on close

$ perl mojo-under-breaky.pl get /breakyname
[Wed Nov 25 14:56:45 2015] [debug] GET "/breakyname"
[Wed Nov 25 14:56:45 2015] [debug] Routing to a callback
[Wed Nov 25 14:56:45 2015] [debug] Your secret passphrase needs to be 
+changed
[Wed Nov 25 14:56:45 2015] [debug] Nothing has been rendered, expectin
+g delayed response
[Wed Nov 25 14:57:00 2015] [debug] Inactivity timeout
Problem loading URL "http://127.0.0.1:2565/breakyname": Premature conn
+ection close
[download]