Javascript web service calls fail after 10.1.5/11.0.01 updates

Question

* Update #2 - I've confirmed that we are seeing errors because the HTTP request is being made as a POST using 10.1.5/11.0.01 in Chrome/Firefox/Safari.  Accessing the same file in IE, the request is made using a GET.  Using Reader 9.5.0 in Chrome also uses a GET.  Can someone please explain why the HTTP request is being submitted as a POST following the 10.1.5 update?
* Update - I have found in my web service log that it is failing with a message that the attempted POST method is not allowed. Could the Reader updates be causing this call to be made as a POST when it was previously a GET?
I am using PDFs with Reader Extensions enabled that make web service calls via javascript.  These calls have been working correctly in multiple environments for months and only began failing with the latest updates.  After the latest Reader updates, these calls fail when using Chrome, Firefox and Safari. 
Internet Explorer works correctly.  Saving files locally and opening them in Reader also works correctly.  It is only running 10.1.5 or 11.0.01 in these specific browsers where this issue occurs.  10.1.4 and 11.0.0 do not experience this issue in any browsers. 
I have tried disabling Enhanced Security and updating Trust Manager to allow Internet Access from PDFs.  Neither change corrected the problem.
Can someone tell me what may have changed in 10.1.5/11.0.01 that would cause these calls to start failing?
The javascript at issue looks like this:
var serviceKeyResult.rawValue = Get(serviceKeyUrl)
The error we get is "Error: Error attempting to read from file: {URL}"

Answer 1

Thanks for pointing that out.  The javacript was implemented by a third party, so I was not aware that the function wasn't part of the standard APIs.  I'll get more detail on what is happening inside that method.
For now we have updated our web services to accept both a GET and a POST to avoid this issue.