Cannot trigger CKEditor WYSIWYG in form API
There are a couple of things that you could try changing:


#input_format and #wysiwyg are not in the list of available properties for a text_format element, so even if they're not causing the error, you should probably remove them.
You shouldn't set the #value of an element like that (unless it's a value type itself). Instead you should use #default_value. In the case of a text_format the #default_value is expecting the text for the text area (since you've already set the format with #format).


I would expect this to work (certainly does for me if memory serves), but if not, check the console for JS errors

return array(
    // ...
    'content'  =&gt; array(
        '#type'    =&gt; 'text_format',
        '#title'   =&gt; t('Content'),
        '#format'  =&gt; 'full_html',
        '#default_value' =&gt; is_null($article) ? '' : $article-&gt;content
    ),
    // ...
);