This issue occurs if the following conditions are true:
If a showModalDialog method is called and the varArgIn option is applied in a modal window of Internet Explorer 11, the dialogArguments property is empty in the second modal window.
If aa showModalDialog method is called in a main page that is not modal in a WebBrowser control, the dialogArguments property is empty in the first modal window.
Additionally, the return value of the showModalDialog() function is NULL or undefined when it should have a valid value.
To resolve this issue, install the most recent cumulative security update for Internet Explorer. To do this, go to Microsoft Update. Additionally, see the technical information about the most recent cumulative security update for Internet Explorer.
Note This update was first included in update 3025390. However, we recommend that you install the February 10, 2015 security update for Internet Explorer (MS15-009) that fixes many other issues in addition to the symptoms that are described in this article.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
See the terminology that Microsoft uses to describe software updates.