I have Magento 2.3.1 installed and UPS was working correctly on it a few weeks ago. But now all the sudden I’m getting the dreaded message that reads: Sorry, no quotes are available for this order at this time. Or it’s just not displaying at all without the option to move to the next step of the order process.
I did, however, find a fix that I wanted to share with you.
The issue was that the UPS service updated their API rules where only HTTPS was required.
Go to Stores > Configuration > Sales > Shipping Methods > UPS
Change the Gateway URL from HTTP to HTTPS at the beginning of the URL.
So it should read: https://www.ups.com/using/services/rave/qcostcgi.cgi
Your UPS calculations should now work on the frontend of Magento.