Fatal error: Call to undefined method stdClass::render() in /home/dev/devsmoke/sites/all/modules/panels/panels.module on line 10

First error line 10:
define('PANELS_REQUIRED_CTOOLS_API', '1.8');

Second error line 1023:
return drupal_render_form($form_context->form_id, $form_context->form);

the whole context includes a reference to ctools:

function panels_render_display(&$display, $renderer = NULL) {
  ctools_include('display-render', 'panels');
  ctools_include('plugins', 'panels');
  ctools_include('context');

  if (!empty($display->context)) {
    if ($form_context = ctools_context_get_form($display->context)) {
      $form_context->form['#theme'] = 'panels_render_display_form';
      $form_context->form['#display'] = &$display;
      $form_context->form['#form_context_id'] = $form_context->id;
      return drupal_render_form($form_context->form_id, $form_context->form);
    }
  }
  return $display->render($renderer);
}

These are the significant errors from Watchdog:

Invalid argument supplied for foreach() in /.../modules/panels/plugins/display_renderers/panels_renderer_standard.class.php on line 225.

Invalid argument supplied for foreach() in /.../modules/panels/panels.module on line 849.

Table 'devsmoke.panels_layout' doesn't exist query: ctools_export_load_object /* admin : ctools_export_load_object */ SELECT * FROM panels_layout t__0 WHERE plugin = 'flexible' in /.../modules/ctools/includes/export.inc on line 379.

Table 'devsmoke.panels_layout' doesn't exist query: ctools_export_load_object /* admin : ctools_export_load_object */ SELECT * FROM panels_layout t__0 WHERE plugin = 'flexible' in /.../modules/ctools/includes/export.inc on line 379.

Unknown column 'title_pane' in 'field list' query: drupal_write_record /* admin : drupal_write_record */ INSERT INTO panels_display (layout, panel_settings, title, hide_title, title_pane) VALUES ('', 'a:1:{s:14:\"style_settings\";a:1:{s:7:\"default\";N;}}', '', 1, 0) in /.../includes/common.inc on line 3545.

The issue was that I was not aware that the upgrade from d5 to d6 had been incompletely executed. I used the instructions here: http://drupal.org/node/515140 ...and it worked.

adding additional message