OnReadyStateComplete does not fire on IFrame

Question

I have setup an IFrame on the Account Entity form in MS dynamics crm. When the OnReadyStateComplete event fires, I do some lookups and construct a custom URL, that calls my server and returns content to be displayed in the iframe. I used "about:blank" as the URL parameter in the setup:

Then, on the events tab, I registered the js library and the event listener - handleIFrame:

Here is the content of the event handler (I removed all unnecessary code to try to get to the bottom of this).

function handleIFrame() {
    alert('handleIFrame');
}

This process is working for full version of CRM - Microsoft Dynamics® CRM Online 2015 Update (7.0.1.247) (DB 7.0.1.237) - it displays the content in the iframe as expected.

However, in Microsoft Dynamics® CRM Online 2015 Update (7.1.1.3113) (DB 7.1.1.3113) it seems that the OnReadyStateComplete event does not fire at all - my alerts in the event handler do not show. Am I correct in assuming this is a difference in versions? Has anyone experienced anything similar? I'm new to CRM, so any advice would be appreciated.

Answer 1

After talking with Microsoft Dynamics CRM support, this is a bug in the 7.1 update. There is a work-around, however. In CRM, navigate to Settings > Administration > System Settings. Then, scroll to the bottom of the popup window - here you will see:

Use legacy form rendering - For compatibility, use the legacy form rendering engine. Note that performance may be adversely affected

Set this to "Yes" and the OnReadyStateComplete will begin to fire.