It seems that starting today, the endpoints will be changing.
Try updating your LUIS endpoint hostname from api.projectoxford.ai to westus.api.cognitive.microsoft.com.
See the image below for the notice and more instructions.
![LUIS Endpoint Update](https://i.stack.imgur.com/sHGkd.jpg)
More info here and here.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…