New Teams meeting add-in is missing from outlook

"This is unfortunate, because like many other organizations, we have added new Teams to computers that still have classic Teams installed, but are now concerned that the add-in will disappear from Outlook whenever classic Teams is uninstalled (which standard users can do from Add & Remove Programs, or Microsoft may do in the future)."

We are aware of this problem, and as you stated, removing classic Teams TODAY will cause the Meeting Add In to fail, if your environment was preventing per-user MSI installs (via GPO, or via AppLocker policies).

@Joel
Your Applocker exclusion might have done the trick.

What specifically did you configure in AppLocker, as there are many ways to skin the cat,
e.g. based on Publisher rule conditions, or a RuleCollection for MSI installs, in which case you must create an exception like
<FilePathCondition Path="%PROGRAMFILES%\WINDOWSAPPS\*\MICROSOFTTEAMSMEETINGADDININSTALLER.MSI" />

Test everything for yourselves of course, because it seems like Teams changes from week to week.

With recent versions of new Teams, you no longer need both versions of Teams installed to have the Meeting add-in in Outlook.

Both new and classic Teams include the Meeting add-in (but different versions). However, on a computer with both new and classic Teams installed, the add-in will be de-registered when classic Teams is uninstalled and as a result, unavailable in Outlook.

By de-registering the add-in, I mean that uninstalling classic Teams changes the registry entries at:

	HKEY\_CLASSES\_ROOT\CLSID\{19A6E644-14E6-4A60-B8D7-DD20610A871D} 

	HKEY\_CLASSES\_ROOT\TeamsAddin.FastConnect\CurVer 

	HKEY\_CLASSES\_ROOT\TeamsAddin.FastConnect.1\CLSID 

	HKEY\_CLASSES\_ROOT\TypeLib\{C0529B10-073A-4754-9BB0-72325D80D122} 

	HKEY\_CLASSES\_ROOT\WOW6432Node\CLSID\{19A6E644-14E6-4A60-B8D7-DD20610A871D}

This is unfortunate, because like many other organizations, we have added new Teams to computers that still have classic Teams installed, but are now concerned that the add-in will disappear from Outlook whenever classic Teams is uninstalled (which standard users can do from Add & Remove Programs, or Microsoft may do in the future).

Microsoft posted some steps that end users could follow to repair the missing Meeting add-in here: https://support.microsoft.com/en-us/office/teams-meeting-add-in-is-missing-in-outlook-desktop-after-updating-to-new-teams-f1dfc3e7-8f48-4320-823b-e13a5aca60c3

What I would really like to see is that 1) installing or even just using new Teams updates the Meeting add-in to the one that comes bundled with new Teams, and 2) the uninstaller for classic Teams leaves the Meeting add-in alone.

Thanks!

the fix that worked for me was to uninstall new teams and re-install it and then confirm the add in was present in outlook. No classic teams needed for me, Goodluck!

Here are the steps to bring back Outlook add-in, no admin needed.

1. Make sure Outlook and New Teams are closed and not running in the background
2. Navigate to the official download page for Microsoft Teams Download Microsoft Teams Desktop and Mobile Apps | Microsoft Teams
3. Scroll all the way down to Frequently asked questions
4. Expand all
5. Download and install the classic Teams app
6. When Teams classic opens, click the upgrade later option
7. Open Outlook and confirm add-in is working
8. Close Microsoft Teams classic
9. Open Microsoft Teams new version
10. Done, everything should be working now

Optional step: Delete all Teams Classic version icon or train user not to use that version. You need to keep both versions install.