For running J!5.1 you must https://fabrikar.com/forums/index.php?wiki/update-from-github/ or include the new file manually https://fabrikar.com/forums/index.php?threads/joomla-5-1-and-fabrik-cannot-find-files-error.54473/post-285151 See also Announcements
Please see our announcement here.
{source}
<?php $user = JFactory::getUser();
echo $user->get('name'); ?>
{/source}
Are you inserting a {fabrik view=element....} into a Joomla article, or something else? If so could you post the url to the article the full {fabrik......} text you are using and the list you are drawing the data from?when I use {ElementName} to show a user name in an article,