Blocked by CORS policy by weebly


i hope anyone can help with this please. i ahve a website on weebly and on it i have jascript url from another server that open a booking system that have been working for years but yesterday it just stopped working the booking calender just say loading and i get this error: is the error below anything to do with Cloudflare? 
:1 Access to XMLHttpRequest at
from origin '' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

Do you know about CORS?

no i know nothing about cors, i wanted to know if the error is from Cloudflare and if i can change some settings there?