Thread:Extension talk:WYSIWYG/Fatal Error when installing WYSIWYG into v1.24/reply

Sounds strange, because there are at least few installations using wysiwyg with MW 1.24. However it will require one manual modification because of protected variable of MW, see Github23.

What kind of environment are you using (MW,php, MySQL,opsys)? ...see downloads -section.

Have you verified that owner:group information of extracted WYSIWYG folder has been properly set on server?

Have you checked instructions here #6 bundle in the end of page (=LocalSettings.php).