This problem appears when you add a pop-up modal window on your main web page, that will show scrolling underneath the modal window on that web page.
Method 1
You can resolve this issue only with CSS on the body tag using following property but its support is limited.
overscroll-behavior: contain
Method 2
A better and secure approach is to use jQuery to prevent scrolling on web page behind modal popup window, replace the Modal-ID-HERE in the following code, with your modal ID and that should resolve the issue.
//make sure you use opening and closing script tag before adding this js code jQuery(document).ready(function(){ jQuery("#Modal-ID-HERE").mouseenter(function(){ jQuery("body").css("overflow", "hidden"); }).mouseleave(function(){ jQuery("body").css("overflow", "visible"); }); });
Hope that helps.