Problem

We have received reports of Word  crashing, hanging, and/or displaying the following warnings after Microsoft's latest update for Office:

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If you click NO on the above message, Word crashes. If you click YES, Word opens but eXtyles is disabled. Any attempts to re-enable eXtyles cause Word to crash.

Diagnosis

The eXtyles engineering team has been working on the problem, and they have isolated the issue to an updated Microsoft Office component. For those interested in the technical details, please see the Appendix at the end of this article.

Solution

Microsoft has published a support article detailing the issue introduced by the Office 2016 Click-to-Run update released this month: VBA forms are not working as expected. In this article, Microsoft describes the potential effects of this update:
In some cases, your Office app may stop responding when you attempt to open a macro-enabled file containing form controls

As of November 2, Microsoft has released a fix for this bug in their latest update, Version 1609 (7369.2054):

On November 2, 2016, we released an update, Version 1609 (7369.2054), which fixes the set of issues related to VBA form controls. To install the update, click File > Account > Update Options > Update Now.


Appendix

eXtyles uses a Microsoft user interface control called a List Box to display the list of files available for comparison in the Compare to Baseline dialog. The latest version of the Microsoft Office component FM20.DLL introduced a bug that causes Word to hang when loading a Visual Basic template that includes this List Box control. As a result, when Word loads eXtyles on application startup, Word hangs when it encounters this control in the eXtyles application.

Interestingly, with the Office Update installed, there are two copies of the FM20.DLL file. The copies, when running 32-bit Windows, are:

  • C:\Windows\System32, version 12.0.6723.5000 with a digital signature applied on June 16, 2015
  • C:\Program Files\Microsoft Office\root\VFS\SystemX86, ¬†version 16.0.7329.1017 with a digital signature applied on October 8, 2016

It's the newer DLL in the Office directory that is at fault.


This problem of conflicting components has been dubbed "DLL Hell.". While many solutions have been proposed over the years, Microsoft has never fully resolved the problem. In the case of eXtyles, the newer version of FM20.DLL is located in the Office directory structure and, because eXtyles is an Office add-in, Word gives the newer version precedence over the older version that is found in the system directory. Short of copying the older version into the Office directory structure, there is not much we can do unless we simply stop using Microsoft's List Box in eXtyles. This is a workaround we will investigate if Microsoft is unable to quickly fix the problem.