Fatal error: Uncaught exception 'Error'

Message: Call to undefined function dnf_get_options_fields()

Stack trace:
#0 /home/downto10/public_html/library/They/Template/TemplateUtil.php(138): require()
#1 /home/downto10/public_html/library/They/Template/TemplateUtil.php(183): They\Template\TemplateUtil::getTemplate('templates/_part...', '', Array, true)
#2 /home/downto10/public_html/library/They/_functions/template.php(27): They\Template\TemplateUtil::getPartial('_nav-off-canvas', NULL, Array, true)
#3 /home/downto10/public_html/site/themes/default_theme/templates/layouts/main.php(4): they_get_partial('_nav-off-canvas')
#4 /home/downto10/public_html/library/They/Template/TemplateUtil.php(138): require('/home/downto10/...')
#5 /home/downto10/public_html/library/They/Template/TemplateUtil.php(199): They\Template\TemplateUtil::getTemplate('templates/layou...', '', Array, true)
#6 /home/downto10/public_html/library/They/_functions/template.php(19): They\Template\TemplateUtil::getLayout('main', NULL, Array, true)
#7 /home/downto10/public_html/site/themes/default_theme/index.php(2): they_get_layout('main')
#8 /home/downto10/public_html/cms/wp-includes/template-loader.php(106): include('/home/downto10/...')
#9 /home/downto10/public_html/cms/wp-blog-header.php(19): require_once('/home/downto10/...')
#10 /home/downto10/public_html/index.php(17): require('/home/downto10/...')
#11 {main}
thrown in /home/downto10/public_html/site/themes/default_theme/templates/_partials/_nav-off-canvas.php on line 2