New USCIS I-129 Form must be used by 5/20/2019
On 3/19/2019 USCIS updated Form I-129, Petition for a Nonimmigrant Worker.
Starting 05/20/19, USCIS will only accept the 01/31/19 edition.
Until then, you can use previous editions: 01/17/17, 12/23/16, 08/13/15, 03/26/15, and 10/23/14.
You can find the edition date at the bottom of the page on the form and instructions.