Continuing from my previous post a few days ago, let’s talk more about application errors when Office add-ins are virtualized. It is pretty easy to resolve most add-in issues with the right methodology. One of the first steps in my methodology is to first determine if the issue is related to the add-in loading or a general application error occurring after the add-in has loaded.
“First Launch Only” Issue or “Every Launch” Issue?
If you have isolated the problem to a load issue, now determine if the problem occurs on first application launch only or on every launch. If it is a first launch issue, the issue resides most likely with the package. If it is on every launch, the issue could be easily in the package or within the configuration and/or user state of the client machine. As mentioned in my previous blog post on the subject, the first place you want to check is the LoadBehavior key in the registry. After that I follow a basic process where on first launch issues, I eliminate LoadBehavior as an issue first, then I determine if registry opacity might be a factor. Registry opacity is where the virtual registry key is configured to either “merge” with the local key or “override” the local key.
If it is an issue that is occurring on all launches, I first eliminate user state as a potential culprit whether it is an incorrect configuration or corrupted configuration. I’ll repair the package first as well as eliminate any other elements related to user state management before I start actually digging into the package configuration.
If the add-in is still failing to load or function properly after loading then you may have to look to ensuring that you have done the basics of planning prior to virtualization. Time to back track a little:
Have We Verified Bitness?
Do we have matching bitness - (i.e. a 64-bit Office application requires a 64-bit COM add-in.) App-V does not change the fact that Office requires the add-ins to match the bitness of the office application. In other words, if you are using a 64-bit version of Office, you do not want to be loading 32-bit add-ins
Are you sure we aren’t missing requirements somewhere?
Have you confirmed that any pre-requisites or middleware required for the add-in have been either included in the add-in package or are installed locally on the client machine? I have been burned by this before. This is the most common reason why an add-in may actually “load” according to Office, but may actually still fail (by either crashing or giving a strange error.) Sometimes the application dependency may appear to be installed but may actually be partially installed. Let’s look at an example:
The Case of the Crashing Add-in
Now here is an interesting case: Let’s say the Office Add-in loads according to the Event Viewer, yet the Add-in still errors out. What is the best way to go about troubleshooting it? In the example below, a component called Cisco ViewMail for Outlook has failed to load in Outlook 2010. We initially get the following error:
‘VMOAddIn’ has fired an exception. Click the ‘Details’ button to see the detailed information about the error.
This error will contain details including a stack trace. This information may prove to be valuable later. This error is exactly what it says. It is not a load error – it is a handled exception or a crash. In this example, it is then followed by a more user-friendly message:
Cisco ViewMail encountered an error while starting and was not able to recover. ViewMail functionality is not available.
So when you get this error, the first thing you will want to do is take a look at the details of the crash. Based upon the error screen – this appears to be a managed code exception (.NET.) When you get these errors – look at these key elements:
Assembly Codebase: file:///Q:/Microsoft_Outlook_2010_V1/VFS/CSIDL_PROGRAM_FILES/Cisco Systems/ViewMail for Outlook/VMOLibrary.DLL
Assembly Full Name: VMOLibrary, Version=9.0.2.1, Culture=neutral, PublicKeyToken=null
Assembly Version: 9.0.2.1
Exception Source: VMOLibrary
Exception Type: System.IO.FileNotFoundException
Exception Message: Could not load file or assembly 'Microsoft.DirectX.DirectSound, Version=1.0.2902.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.
So in the case of the above error, we see something very straight forward: A missing file – Microsoft.DirectX.DirectSound. Looking at the list of installed programs and updates, I see that the DirectX components are indeed installed.
Know the Add-in
Before you troubleshoot further – it would probably be a good idea to have a known good installation (where the add-in is installed and working normally on a native installation.) I usually compare Process Monitor captures of the known good with a trace of the reproduced error. Before I even do this, though, I need to know what I will be looking for. In most cases with add-ins, there will be a loading of the add-in (usually a DLL) by a base executable (in this case, the Office application is Outlook so the EXE will be OUTLOOK.EXE.)
What are the EXE’s and DLL’s for ViewMail?
To get this information, I can either look at a local installation or I can open a command prompt in the bubble and browse the VFS. Once I know what these DLL’s are and where they are located, I can then proceed to weed through a Process Monitor capture of the failure. I first add a PATH filter in ProcMon using the CONTAINS operand and the use the keyword “ViewMail.” This takes my filter down from nearly 30,000 events down to 1,217 items. Next I look to add another filter. Since the error “Could not load file or assembly 'Microsoft.DirectX.DirectSound” was in regards to a file or assembly, I now add an additional filter for the
operation “LoadImage.” This knocked the entries down to 29 events but EVERYONE OF THEM SHOWED SUCCESS!
Does this mean we are taking crazy pills? No, this just means you have eliminated the simple issue of a failure to load a DLL. The “file” aspect of that error has been eliminated. We are now simply chasing down a .NET assembly. So now we need to hone in on the codebase of the error – narrowing the context:
Assembly Codebase: file:///Q:/Microsoft_Outlook_2010_V1/VFS/CSIDL_PROGRAM_FILES/Cisco Systems/ViewMail for Outlook/VMOLibrary.DLL
I’m going to go back to the Process Monitor capture and return to the point where the successful LoadImage operation of VMOLibrary.DLL occurred. I reset the filter from this point (making sure this selection remains highlighted.) Anything before this point is irrelevant. I begin to start walking down the trace, systematically eliminating irrelevant processes (right-clicking them and selecting “exclude” – BUT - BE SURE YOU KNOW WHAT YOU ARE EXCLUDING IS IRRELEVANT.)
I walk through the loading of the file VMOLibrary.DLL until the result is END_OF_FILE which means the file has been completely loaded. Continuing on in the trace, I notice it is now walking the .NET assembly registrations and finding begins to hit PATH_NOT_FOUND error and events start to occur where it begins to write to an error log. I take note of the assembly name in the error: 'Microsoft.DirectX.DirectSound.’ It is as if it thinks that the DirectSound component of DirectX is not installed – but I verified it was installed prior to troubleshooting. However, I go to the C:\Windows\Assemblies folder and sure enough, it is not there.
How did I know to look there?
Activity to this special folder (C:\Windows Assemblies) involves looking for actual activity going to the .NET Global Assembly Cache (GAC.) When looking at Process Monitor traces, all activity in the Global Assembly Cache is logged by direct path in ProcMon as
- C:\WINNT\assembly\GAC_MSIL
- C:\WINNT\assembly\GAC
- C:\WINNT\assembly\GAC_32
So the problem we had was that while DirectX was installed, the proper .NET DirectX assemblies were not registered in the GAC. Now if this ever happens you want to make sure the binaries for the DirectX managed Code components are there. In this case – the files were actually in C:\WINNT\Microsoft.NET\DirectX
for Managed Code\1.0.2902.0 BUT they were not actually registered to the GAC. If the files were not even on the machine – a reinstallation of DirectX is in order (plus updates.) If the files are there but not registered in the global assembly cache then you could leverage REGASM:
REGASM.exe - http://msdn.microsoft.com/en-us/library/tzat5yw6.aspx
And register those assemblies manually – my recommendation would be to simplify things and just reinstall DirectX. Then you will see the assemblies properly registered.
NOTE: Unregistered assemblies may not show up in a DXDiag report but the .NET assemblies inventory for DirectX is part of the output as demonstrated with a before and after comparison using BeyondCompare.
