This is for when Office 365 gives an error message when attempting to convert a terminated employee’s mailbox into a shared mailbox. It uses powershell to connect and requires admin login for the account itself. (I have not tested this with our logins that have partner portal access. If those work please update this wiki stating is as such.)
Launch powershell and input the command:
$UserCredential = Get-Credential
It will launch a credentials window. Use the admin account user name and password. After putting in the credendials input the next commands in sequence allowing for the prompt to restore after each command:
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection
Import-PSSession $Session -DisableNameChecking
Set-Mailbox [usermailbox] -Type Shared
Where [usermailbox] is the terminated employee. If no error message happens then congratulations, you did a thing. Disconnect from the session before closing the powershell window by inputing:
Remove-PSSession $Session
You can now assign permissions and remove licenses in the admin portal.