I was working with a customer recently who wanted to convert a shared mailbox back to a user and found that I was given the following error message:
Error on proxy command ‘Set-Mailbox -Type:’Regular’ -Identity:’BLAH’ -Confirm:$False -Force:$True’ to server AMXPR07MB088.eurprd07.prod.outlook.com: Server version 1941996335, Proxy method PSWS: Request return error with following error message: The remote server returned an error: (500) Internal Server Error…
After some digging and a quite conversation with my contacts within Microsoft, it was discussed that this is a known issue which to affects all EMEA customers. However being the bearer of good news there is a workaround:
Instead of connecting to ExO Ps the normal way you have to use the following: New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://ps.outlook.com/powershell/?targetserver=AMXPR07MB088.eurprd07.prod.outlook.com-Credential $Cred -Authentication Basic -AllowRedirection
Ensuring a targetserver is set and the target server should be the server in the error message as also shown above.
MS are aware of this bug and have advised that this will be resolved in the next build release which should be within the next quarter.