From time to time i run into a little problem with the Office 365 Admin Center when trying to convert user mailboxes into shared mailboxes.
when this occours i usualy just use Powershell to convert the mailbox into shared mailbox.
To do this you have to connect your Powershell to the Office 365 tenant and run a oneliner for converting the mailbox.
Here is how to connect to Office 365:
Import-Module MSOnline
$O365Cred = Get-Credential “adminuser@YOURTENANT.onmicrosoft.com”
$O365Session = New-PSSession –ConfigurationName Microsoft.Exchange -ConnectionUri https://ps.outlook.com/powershell -Credential $O365Cred -Authentication Basic -AllowRedirection
Import-PSSession $O365Session
Connect-MsolService -Credential $O365Cred
When connected then use this single line to convert the mailbox:
Set-Mailbox “Your@mailbox.no” -Type shared
