Livecycle - form1.execValidate is not a function! Then Reader crashes

Question

error message: form1.execValidate is not a function. but this has worked fine for years!

Last week the client (large bank) rolled out a new version of Adobe Reader XI 11.0.21. Perhaps registry keys were changed as well - don't know.

So now all livecycle forms are crashing. Below is one error message seen on the console followed by the crash.

The code being used has been executed 10K+ times over ~5 years, over roughly 5 different forms over many versions.

form1.FirstPage.sfBody.sfSectionB.sfEnder.SendReferral::click - (JavaScript, client)
var res = form1.execValidate();     // does form validation, if all good returns true
if (res) {
  cLookFeel.fMailTo(event.target); 
}

(Code is attached to the click method on a button, cLookFeel is the name of my code block.)

And strangely - Reader then seems to (often) crash. Go figure.

followed by a crash:

Answer 1

Okay, turns out it's a known bug by Adobe on 11.0.21. They've issued a fix.

https://helpx.adobe.com/acrobat/release-note/acrobat-dc-august-11-2017.html