How to fix this?
Topic on Extension talk:AJAXPoll
Please report this issue (as indicated on https://www.mediawiki.org/wiki/Extension_talk:AJAXPoll ) as an issue in our bug tracker https://phabricator.wikimedia.org/maniphest/task/create/?projects=MediaWiki-extensions-AJAX-Poll and please report some more details (MediaWiki version, AJAXPoll version) as reported in Special:Version of your installation.