Don't use the absolute url

resources/views/subscribe.blade.php

@@ -24,7 +24,7 @@
     @include('partials.dashboard.errors')
 
     <h1>{{ trans('cachet.subscriber.subscribe') }}</h1>
-    <form action="{{ route('subscribe') }}" method="post">
+    <form action="{{ route('subscribe', [], false) }}" method="post">
         <input type="hidden" name="_token" value="{{ csrf_token() }}">
         <div class="form-group">
             <label for="email">{{ trans('cachet.subscriber.email.subscribe') }}</label>