Flash Sandbox Security error just started popping up in the last day. Dead in water.

[RoyceSimpson]

I've got a suite of Flex/AGS based apps hosted locally that have been running for years.

In the past day or so, I've been getting the following sandbox security error ONLY in IE browsers:

SecurityError: Error #3769: Security sandbox violation: Cannot send HTTP headers when using navigateToUrl().

Here is our crossdomain.xml file: http://maps.larimer.org/crossdomain.xml

The error only occurs when you try to use our alivepdf printing process (which again has worked with no issues for years). I realize this isn't an esri issue but I'm hoping there is some expertise on board here that could lend a hand. As it is, all my pdf creation capabilities are dead in the water for IE until I can resolve this issue.

If you go to maps.larimer.org/lil and click the "pdf" button, then "create pdf", the progress bar will either just hang or you'll get the above flash error.

The pdf creation process works just fine in Firefox and works occasionally on Chrome (but chrome has a separate pdf issue not related to this).

Any tips or help would be greatly appreciated. I've exhausted all my resources on this one.
Thanks,
-Royce

[RoyceSimpson]

Last I saw, Adobe was going to fix this in the Flash Player by allowing simple headers.  The reality is that may not fix your specific issue.  Since I've implemented the above code change, I haven't been following the saga but here's the conversation:  Bug#3759971 - Security error #3769 is too excessive, breaks navigateToUrl()‌