VSTO Add-in not loading. Looks like VSTO itself is not loading?

2
votes

I have an Outlook Add-in. In Outlook 2016 (Office 365 desktop version) it will not load. 32 bit Office install on Windows 10 64 bit. It appears that the VSTO runtime itself is not loading. The add-in does not appear. It doesn't appear in the disabled add-ins, nor in the Manage Add-ins anywhere to be enabled.

The add-in registry entry for being always enabled is correctly added. I have verified that the correct .NET version and the VSTO runtime are all installed. I have set 

VSTO_SUPPRESSDISPLAYALERTS 0
VSTO_LOGALERTS 1

and receive no data back from them.

I have also verified that the registry keys are correct. LoadBehavior is set to 3 and Manifest is pointing to the correctly installed file.

What is even more curious is that it did load at one point and worked fine, but seemingly all of a sudden it will not.

Has anyone run into this or know anything I can check to see what is going on?

1
vstooutlook-addinoutlook-2016
Did you check the add-in settings (i.e. LoadBehavior) in both HKLM and HKCU? Does the add-in appear under File > Options > Add-ins? How is it listed there? – Dirk Vollmar
It is not listed there, which is what it is baffling to me. The addin registry keys appear under HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Office\Outlook\Addins\MyAddin and are correct. Do they need to be in the user hive as well? It is installed in Program Files(x86) – Corv1nus
How about File > Slow and Disabled COM Add-ins? – Dirk Vollmar
It is not there either. I have the value at 1 for HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Resiliency\DoNotDisableAddinList\MyAddin as well. What is baffling me is that it did work for a couple of days and now it does not. I'm looking into Outlook changes during that time frame, like an update or something that might have caused it. – Corv1nus

1 Answers

0
votes

In the event anyone runs into this, here are the steps used to solve the problem for me.

  • Uninstall my add-in
  • Uninstall the VSTO runtime
  • Uninstall Outlook, including any non-2016 components if any remain
  • Reinstall Outlook (2016 should have the run time)
  • Reinstall the add-in

It's a pain, but it worked.