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
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I posted I think in reply to one of your earlier threads, a walk through of how to plan a project, did you do this? If so can you post what you came up with? If not well !
It sounds like I should translate as much as I can into English anyway, ye?