Outlook add-in not appearing consistently

[dex3703]

We are having intermittent problems with getting a managed code Outlook
add-in to work consistently with some computers. The add-in won't start, and
Outlook will say it was disabled on startup due to an error. Its LoadBehavior
value is set to 3 in the registry.

We've found some articles related to this problem but haven't been able to
lick the problem so far. I found http://support.microsoft.com/kb/908002/
which seems to be a good lead but it seems like the dll's it fixes are
already updated on the problem machine.

Any help or suggestions appreciated.
Thanks in advance,
Derek

 

[Ken Slovak - [MVP - Outlook]]

That KB only applies when Office is installed prior to installation of the
Framework. Otherwise it's irrelevant.

Disabling an addin usually occurs if there's an unhandled exception that
might cause the addin to crash or to crash Outlook. The other common factor
is not correctly setting the security of the deployment to set full trust on
the executing assemblies.

Do you have error logging enabled with the addin? The error log from that
computer might provide you with a clue if it ran at all, if it never ran
then I'd suspect some problem with the security, that's usually what it
comes to (assuming all the pre-requisites are installed).

 

[dex3703]

Thanks for the response, which I've passed along to the developers working on
this. The plugin does seem to be throwing an exception, but it is not being
caught or logged for some reason. We'll check out the security angle too.

Derek

 

[dex3703]

We found the problem, which was unrelated to any of these suggestions. The
office.dll (for 12) and Microsoft.Office.Interop.Outlook.dll were missing on
my computer. Once these were added to the GAC the plugin worked fine.

A little history on our issue. We have a plugin that works with Outlook to
talk to our web application, and lets you save over Outlook items. There were
ongoing problems with the plugin not appearing on client machines early on,
but most of these were resolved when dll conflicts were fixed and some
erroneous compiler directives were removed. Now the problem happens only
rarely, and it’s been difficult for our people to figure it out, since we
don’t have any machines here that would exhibit the problem.

Then my new computer here wouldn’t load the plugin. The Outlook trust center
would just report the plugin as disabled and that there was an error starting
the COM addin.

It turns out we found the problem in trying to attach a debugger to the
addin code. I couldn’t get the office.dll and the
Microsoft.Office.Interop.Outlook.dll references to resolve. It turns out
they’re not on my computer. Somehow they were not installed (or are invisible
or have somehow been changed by an update) and the addin can’t run without
them, even though Office itself somehow can. Once we put these dll’s in the
GAC the plugin worked fine.

Can anybody provide any insight to these missing dll's? I tried repairing
Office 12 but it didn't install them.

Thanks in advance,
Derek

 

[Ken Slovak - [MVP - Outlook]]

Your deployment project should always check for and if necessary install any
prerequisites such as PIA's, the Framework, VSTO runtime, etc.