If your forms use the V4.0 client API (crmForm), you may encounter script errors after your Microsoft Dynamics CRM Online organization is updated to the December 2012 Service Update. You may see a dialog appear that says "Undefined", or you may see an error in the bottom left corner of the form that says "Error on page". Other various script errors may appear.
The December 2012 Service Update for Microsoft Dynamics CRM introduced a new System Setting that controls whether or not HTML Components (HTC) are included in Microsoft Dynamics CRM forms. This setting is disabled by default in Microsoft Dynamics CRM Online.
The following crmForm properties require HTC:
1. Log into the Microsoft Dynamics CRM web application as a System Administrator.
2. Click Settings, click Administration, and then click System Settings.
3. Click the Customization tab.
4. Click the checkbox next to the setting labeled "Include HTC Support in Microsoft Dynamics CRM forms"
5. Click OK.
The crmForm API was deprecated with the Microsoft Dynamics CRM 2011 release. For more information on this topic and other potential causes of script errors after the December 2012 Service Update, refer to the following Blog posts: