EntityMalformedException: Missing bundle property on entity of type node in modal
EntityMalformedException: Missing bundle property on entity of type node


This means that at some point in code when the node entity should be handled, it is unclear what type (bundle) that is. Now when you look at node_form() you see that it expects a node object as a parameter. If that's not given the node add form doesn't know what fields and properties to render because the node type can't be identified. Looking further into node_add(), which is the function normally called to create a new node of a specific type, I think you could go along the following lines (completely untested):

global $user;
ctools_include('modal');
ctools_include('ajax');
$node = (object) array(
  'uid' =&gt; $user-&gt;uid,
  'name' =&gt; (isset($user-&gt;name) ? $user-&gt;name : ''),
  'type' =&gt; 'page',
  'language' =&gt; LANGUAGE_NONE,
);
$form_state = array(
  'ajax' =&gt; TRUE,
  'build_info' =&gt; array(
    'args' =&gt; array($node),
  ),
);
module_load_include('inc', 'node', 'node.pages');
$output = ctools_modal_form_wrapper('page_node_form', $form_state);