Unable to load Teams AddIn

Question

We have devices with the Classic version of both Teams and Outlook 365 Enterprise installed. Existing devices have the Teams AddIn working within Outlook.

Newly imaged devices, show the Teams Addin, installed however it cannot be enabled in Outlook. A previously functional device with the Teams AddIn working was used for a test in which we deleted the AddIn and attempted to add it back, we were unable to do so.

The behavior we are seeing is that when you Click Add for the Com Add-ins, and browse to the Microsoft.Teams.AddinLoader.dll under the users Appdata, and click Ok, then window closes and absolutely nothing happens. No error, not prompt, nothing. If we click another DLL such as (Microsoft.Teams.MeetingAddin.dll) we get an error saying it's not valid.

We are enforcing Outlook/Office 365 STIG settings on our devices and I've tried disabling AntiVirus and reverting various restrictions with no change in behavior. I've even ran Procmon and tried to enable it and haven't found anything specific or telltale error or block.

The only possibly thing I saw was an error code in Procmon with the source process of Explorer.exe (0xC000CF13) trying to perform an operation tied to the folder containing the MicrosoftTeamsAddin.

Not sure what to check next or where to go from here.

Answer 1

Hi @Joshua Wyman Based on your description, here are some steps you can take to troubleshoot and resolve the problem:

1. Verify that the following policies are assigned to the affected users: A Teams Upgrade policy which enables scheduling meetings in Teams. For more information, see Set your coexistence and upgrade settings. A Teams Meeting policy that permits the Outlook add-in to be installed. For more information, see Meeting policy settings.
2. If you're an administrator, you can use the following diagnostic tool to validate that a user has the correct policies to enable the Teams Outlook add-in. Go to the Microsoft 365 admin center. Click on Run Tests: Teams Add-in Missing in Outlook. Enter the email address of the user experiencing issues with the Teams Outlook add-in and select Run Tests. The diagnostic will provide next steps to resolve any tenant or policy configuration issues and validate the user’s configuration.
3. If policies are assigned correctly but the add-in still won’t install, or if you’re not an administrator, download and run the Microsoft Support and Recovery Assistant.
4. If you'd like to perform the checks and make the fixes manually, please follow the article.
5. If you still don't see the Teams Meeting add-in, make sure it's enabled in Outlook. In Outlook, select File > Options. In the Outlook Options dialog box, select the Add-ins tab. Check whether Microsoft Teams Meeting Add-in for Microsoft Office is listed in the Active Application Add-ins list. If the add-in is not listed in the list of active applications, and you see the Teams Meeting Add-in listed in the Disabled Application Add-ins list, select Manage > COM Add-ins and then select Go… Select the checkbox next to Microsoft Teams Meeting Add-in for Microsoft Office. Select OK on all the dialog boxes that are open and restart Outlook.
6. If the add-in still doesn't appear, please check the registry settings.

For more details, you may refer to the article. Hope the above information is helpful for you!

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