This articles describes solutions to enable add-ins that are marked as inactive in Outlook but they are NOT marked as disabled. Outlook 2010 and Outlook 2013 actually have 3 status labels for add-ins: enabled, disabled and inactive. Most people confuse an inactive add-in with a disabled add-in, but they are not really the same thing.

Sometimes, it may happen that Outlook deactivates an add-in (or all your add-ins) without marking it as being disabled. It may end up making all your Outlook add-ins inactive, but at the same time they are not listed in the Disabled Items list.

To better showcase the situation, here is a list of inactive Outlook add-ins (notice there is also a Disabled Add-in below the Inactive list):

If you open the COM Add-ins manager (by clicking on the Manage COM add-ins “Go” button, in the above screenshot), these inactive add-ins are not marked as being enabled, but they are also not marked as being disabled. In fact, their “Load Behavior” is set to “Unloaded”:

Enabling inactive / unloaded add-ins is trickier than enabling a disabled add-in. Normally, you should be able to enable them simply by marking the related check-box in the COM Add-ins manager window (as in the above screenshot or as detailed in this Disabled Add-ins tutorial). In practice, Outlook may keep deactivating / unloading these add-ins every time when it restarts.

Enabling inactive Outlook add-ins that keep being unloaded

If Outlook keeps deactivating an add-in, first of all try to uninstall & reinstall the given add-in. If it doesn’t solve the issue and the add-in is still being displayed as inactive, please follow these steps to activate the add-in:

Exit Outlook and uninstall the given Outlook add-in from your Windows Control Panel (see Add/Remove Programs or Uninstall Programs, depending on your Windows version).

Open your Windows registry (run regedit.exe) and locate the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Resiliency 

Replace 15.0 with your actual Outlook version: 15.0 means Outlook 2013, 14.0 means Outlook 2010, 13.0 means Outlook 2007, etc. Remove the REG_BINARY keys found in DisabledItems and CrashingAddinList:

HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins

Remove the keys that refer to your troubled Outlook add-in. If you want to fix the OneNote Outlook add-in, remove the entry named OneNote.OutlookAddin.

Reinstall the related Outlook add-in and restart Outlook: it should be loading fine now, without being listed as an inactive add-in.