Introduction

When updating the SEAS add-in to a new version, if you received the error shown above, it is likely that your organization installed the add-in using an installation mechanism other than the M365 Admin Center. Examples of deployment methods that would cause this error include centralized deployments that used the Exchange Admin Center (EAC), or installations via Exchange PowerShell. Since these installation methods do not involve Azure Active Directory (AD), it would not be listed in the M365 Admin Center as an integrated app.

Recently, Microsoft has been moving the M365 Admin Center towards being the preferred installation method for Office/Outlook add-ins. Unfortunately, as part of the transition, it seems Microsoft removed visibility of these apps in the EAC from the M365 Admin Center and has not provided a UI interface to deal with this scenario. 

Therefore, we propose a solution to this issue using PowerShell.

Procedure

In an elevated PowerShell window (i.e. "Run as Administrator") run the following commands:

Ensure the "ExhangeOnlineManagement" module is installed.

Install-Module -Name ExchangeOnlineManagement

Execute the module

Import-Module ExchangeOnlineManagement

If an error appears containing "ExchangeOnlineManagement.psm1 cannot be
loaded because running scripts is disabled on this system." run the following and re-execute the module.

Set-ExecutionPolicy -ExecutionPolicy RemoteSigned

Connect to your M365 tenant (you will be prompted to authenticate to the tenant, use an account with administrator privileges on the tenant)

Connect-ExchangeOnline

List the installed apps. This will include add-ins which do not appear in the M365 Admin center.

Get-App | Format-Table DisplayName,AppVersion,AppId,Enabled,DefaultStateForUser

Remove the app by ID:

Remove-App -Identity "<AppId>" -OrganizationApp

If you rerun the "Get-App" command, the App will still be listed. However, you should now be able to do a fresh install of the SEAS add-in from the M365 Admin Center.