I have error reporting on in LocalSettings.php:
error_reporting( -1 ); ini_set( 'display_errors', 1 );
Now every time one of my pages uses a secure html block (from https://www.mediawiki.org/wiki/Extension:Secure_HTML) I get the message:
Strict Standards: call_user_func_array() expects parameter 1 to be a valid callback, non-static method SecureHTML::secureHTMLRender() should not be called statically in /mediawiki/includes/parser/Parser.php on line 4279
If I have 3 secure html elements on one page, I get that message 3 times.
This issue was also reported before at https://www.mediawiki.org/wiki/Topic:Ty2uwamgpnofikum