Payor Name-1 on the D-40WH almost certainly comes from your first federal W-2 or 1099-MISC. The official DC form has only 13 spaces on the form (the TurboTax version might have more - I haven't seen it).

The first thing I would do is edit your first W-2 and shorten the Employer's Name to less than 20 characters Then do the Review again and see if the error goes away. If so, you have found the problem. If the error persists, then try the other W-2s or 1099s (if any), or shorten the name to 15 characters - although users have replied that shortening to 20 normally solved the problem.

Note that shortening the name of the employer on the W-2 won't be a problem, if you've made sure that the employer's EIN on the W-2 is correctly entered.