OSMap Documentation

How to Fix Error "Attempt to modify property "children" on null"

In some use cases, you may encounter the "Attempt to modify property "children" on null" error when trying to view your HTML sitemap:

The "Attempt to modify property" error displayed on a front page of a Joomla site

Here is how to resolve this error:

  • Open up the OSMap extension in your Joomla admin panel.
  • In the top right corner of the screen, click "Options".
  • Set the "Show External Links" parameter to "Yes" or to "Only in HTML Sitemap":

The "Show External Links" parameter set to Yes