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.
We made some changes to the PDF code a day or two ago. Can you see if the latest github code makes any difference to this error?
-- hugh
i couldnt log into the admin with the username you posted.
Can I double check you have a folder /libraries/dompdf in your site?
Can you confirm that in fabrik's global configuration you have debugging->debug pdf = "off"
-Rob
Perhaps if you had never saved the global config since that option was added, there might have been a mismatch between the default value that we use if one wasn't recorded for that option and the default shown in the config.Do you have an ideia why the "hell" this has been solved by setting the PDF degub to on and then put it back to off