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
See Announcement
We are still working on the Joomla update.
Did you edit and re-save the Fabrik connection so Fabrik does know about the new database?I have changed the host and thus all files have been transferred to the new location...What could be the reason...?