WordPress NextGEN Gallery doesn’t work in some themes – workaroud

Symptoms:

  • visual editor in backend doesn’t work;
  • NextGen option doesn’t show up;
  • everything works ater switching to some default theme like “tweenty-eleven”;
  • in html source code of the webpage you can see wrong links to CSS and JS files with duplicated domain name;

Versions: WordPress 4.7.3; NextGen: 2.2.1
Comment the line number about 191 in file “wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/mvc/package.module.mvc.php”:

$retval = '/' . $retval;

Proper solution:

Theme author should properly set

current_theme_supports('soil-relative-urls') || current_theme_supports('root-relative-urls')

.