Write-n-Cite is producing a “Length is null or not an object” message.

If you are using Write-n-Cite III (WNC III), start by using the "Tools" menu to "Revert to WNC v. 2 document". WNC v.2 has no hidden code. All empty citation placeholders will be visible.
2. Once you have converted to WNC v. 2, or if you are using WNC 2, use Word's Find feature to find and delete instances of

{{}}

{{ }}

and

{{ }}

3. Save your changes.
4. If you are using WNC III, use the WNC "Tools" menu to "Convert to WNC III"
5. Click on the “Bibliography” button and “Create Bibliography”

I'm getting a -- 'length' is null or not an object -- error message. What should I do?

If you are seeing this message, you are probably using Write-n-Cite III. Sometimes Write-n-Cite III users insert citations in a specific location and then realize they don't want any citations in that location. Using the "Edit Citation" link it is possible to remove the inserted references, but it is easy to forget to remove the curly-Q brackets defining the in-text location as an in-text citation site. Use Ctl F or Edit->Find to search for instances of {{. Alternately, search for {{}}, then for {{ }}, then for {{ }}, etc. to find empty sets of curly-Q brackets separated by different numbers of spaces. When you find an empty {{ }}, highlight it and delete it.

Some Ref Works users will remember that it used to be necessary to revert to Write-n-Cite II before removing the {{}}'s and then convert back to Write-n-Cite III. Fortunately, all this reverting and converting is no longer necessary.