After upgrade of dynamics CRM 8.2 to 9.0 jQuery start breaking or you will receive $ undefined error.
This blog will explain how to resolve this issue jQuery ($) is not defined in dynamics 365 sales.
As you can see in below screen shot it shows that $ is not defined as it has more than 1 jQuery library loaded and it try to get the definition from another library which does not contains the definition of our library.
As you can see in the below screen shot we have included no conflict script.
This will resolve the issue of conflict and you will not receive the error related to conflict.
You can refer the below link for more information on conflict.