'OSF is undefined' script error in o15apptofilemappingtable.js file when Mail App launched

Question

I created a Mail App for Office using Visual Studio 2013 "App for Office" project template. After I installed the app in my OWA, I am get intermittent errors when launching the app in IE9.
The error is "'OSF' is undefined' and happens when executing script in o15apptofilemappingtable.js file, which is part of Office API. Other browsers are not affected.
Does anyone has an idea how to fix this. The screenshot is attached below:

Answer 1

Hi Philip,
It's not an issue with a 3rd party. I created a brand new App for Office project in Visual Studio 2013. If you want, I can provide you the code, but it is really only pure Microsoft code, no changes of my own.  I deployed it in my IIS and installed
in Exchange 2013 CU6. I am able to repro the issue with IE9 on Windows 7 and Windows 2008 R2. Here are the steps to reproduce it:
1.  Check "Display a notification about every script error" and enabled debuggers in IE 9 Internet Options.
2. Open a message inside the Inbox and start the App. Trigger some events inside the app. In the VS2013 template app, I am using, there are some click handlers attached to the Sender's name. After that, open another message and launch
the app.
3. Repeat few times. It may not reproduce on the first try.
The issue usually happens after onblur fires when switching between messages in the inbox while the app is opened or when loading the next message. It looks like onblur fires after some javascript object were already destroyed.
Below are screenshots of the VS2013 template app.
Thank you,
Tomasz