Thread:Extension talk:WYSIWYG/WYSIWYG-CKEditor extension causes "edit" page to load blank/reply (3)

Have you checked sample settings from README.md (see section "File: LocalSettings.php") and copied all of them as last section in your LocalSettings.php ?

Have you tried to create brand new wikipage containing only few lines of plain text using wywiwyg (this is just testing that your setup is ok) ?

Do you have any php errors in logs on server?

What versions do you have: browser / MW / db / php ?