I have tried to access Illustrator Help... several times now via the Help Menu option of the same name as well as the F1 key, and Safari yielded the following "Page Not Found" error message, saying "The page you are trying to access was not found. Please check your URL for typos and try again."

This is the first time I have seen this bug, which is now repeatable and reliable..

Updated Illustrator CC 2019 to version 23.0.6 last night. On a MacBook Pro Retina mid-2014 running MacOS 10.14.6.