Microsoft introduced a new feature called Turbo Forms with CRM 2015 Update 1 which improved form load performance. You might have systems that contain javascript code that are not supported/crash when Turbo Forms are enabled. There are couple of ways to get around this.
One, is to toggle the feature by going into Settings > Administration > Enable Legacy Forms.
Second, is to upgrade the javascript code. While upgrading the javascript code, it might be a good idea to have a fallback mechanism so that if Turbo Forms are disabled, code continue to function.
Here is a piece of code that you can use to detect if Turbo Forms are enabled or not.
var turboFormsEnabled = Xrm.Internal.isTurboForm();
Please note, this function is not documented for public use, therefore consider this as unsupported Image may be NSFW.
Clik here to view.
A bit of insight into this Xrm.Internal function; this function calls Mscrm.Utilities.isTurboForm which then checks window.IsTurboForm; if window.IsTurboForm is undefined, returns false, otherwise true.
Image may be NSFW.Clik here to view.
