WfLoadExtensionMessages

wfLoadExtensionMessages is a deprecated MediaWiki function. It was a no-op since 1.16, and was removed entirely in 1.21.

If you are upgrading a wiki that uses old extensions, you may see an error such as:

Fatal error: Call to undefined function wfLoadExtensionMessages in /home/example/www/wiki.example.com/w/extensions/wigo3/wigo3.php on line 50

Fortunately, since it was a no-op, you can comment it out of your extension.