Fatal error: Call to undefined function node_form_validate() in .../includes/form.inc on line 1414

Solution to Drupal 7 error:

Error:
Fatal error: Call to undefined function node_form_validate() in .../includes/form.inc on line 1414

Solution:
Place next peace of code to your module.

module_load_include('inc', 'node', 'node.pages');