Outlook add-in disabled; Impossible to re-enable

Question

I have an add-in in Outlook. About a month ago it got disabled and no longer loads.

I went to file - Manage COM Add-ins, and it shows up under Slow and Disabled Add-ins.

Under options it only has one option, "Enable this add-in". (not 4 different options and I saw in some screenshots) However, clicking on this does absolutely nothing.

I also tried some registry patches as described here, to no avail: https://community.spiceworks.com/topic/1978405-outlook-2016-always-disables-add-in

Anything else I can do? first off, why is only one option showing under the Outlook Add-ins?

Answer 1

There are multiple reasons why your add-in can be disabled. The cause could be related to the prerequisites missed on the target machine, incompatible dependent assemblies, not handled exceptions at runtime, log-running tasks which slows down the host application. Starting from Office 2013 Outlook supports add-in resiliency, meaning that apps will disable an add-in if it performs slowly. While most add-ins will not be disabled by the add-in disabling feature, you don't want your add-in to be disabled consistently. Following are some suggestions for improving add-in performance:

• Prefer native COM add-ins over managed add-ins because managed add-ins must incur the overhead of loading the .NET Framework during Outlook startup.
• If you have long-running tasks such as making an expensive connection to a database, defer those tasks to occur after startup.
• If possible, cache data locally rather than making expensive network calls during the FolderSwitch and BeforeFolderSwitch events of an explorer, or Open events of an item.
• Be aware that all calls to the Outlook object model execute on Outlook's main foreground thread. Avoid making long-running Outlook object model calls if possible.
• In Outlook 2013, calls to the Outlook object model return E_RPC_WRONG_THREAD when the Outlook object model is called from a background thread.
• Polling is an expensive operation, so always prefer an event-driven model over polling.

Read more about that in the Support for keeping add-ins enabled article.