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.
Would this method be of help, click on this link: http://fabrikar.com/forums/index.php?threads/cannot-redeclare-class-jform.34129/Thanks for info...
I am getting this:
Fatal error: Cannot redeclare class JFormField in /home/uros/sites/dev.urosk.net/www.mis.si/plugins/system/jat3/jat3/core/joomla/form/field.php on line 20
I googled for solution, but found only this:
http://fabrikar.com/forums/index.php?threads/fatal-error-cannot-redeclare-class-jformfield.36405/
This solution doesnt work....