Sitemap error?

Question

MODX

Sitemap in google webmaster gives an error "invalid date".
Here is the map code

<url>      
  <loc></loc>
  <lastmod>[[+createdon]]</lastmod>
  <priority>0.5</priority>
  <changefreq>weekly</changefreq>
</url>

and gives the date
<lastmod>2016-12-27 20:11:30</lastmod>

Answer 1

Use pdoSitemap