Discovery/Sync o365 - EXO 3.9 breaks poweshell calls

Recently released Microsoft EXO v3.9 breaks powershell calls used by Discovery and Sync, resulting in the below error¹. To fix this error, a modification must be made to Unitysync’s o365.ps1 file.

(This change will be added to the next Unitysync version).

1. Goto the Unitsync installation folder.
   UnitySync/bin

2. Save a copy of o365.ps1 as o365.ps1-orig

3. Edit o365.ps1

4. Change the following 2 lines, adding -DisableWAM to the end of the line.

5. Save the changes and run Discovery/Simulation to confirm.

Line 58:
Connect-ExchangeOnline -ExchangeEnvironmentName $environ -ShowBanner:$false -ShowProgress $false -Credential $UserCredential -PSSessionOption $proxysettings -DisableWAM

Line 80: Connect-ExchangeOnline -ShowBanner:$false -ShowProgress $false -Credential $UserCredential -PSSessionOption $proxysettings -DisableWAM

[1] The error below will appear in the log:

Starting Powershell process : 11/26/25 09:01:44  
*************************** Powershell Environment ***************************  
exo version=3.9.0  
powershell version=7.4.0  
****************************************************************************** 

 Powershell Error Crit          | Unknown Status: Unexpected 
Error: 0xffffffff80070520  
Context: (pii)  
Tag: 0x21420087 (error code -2147023584) (internal error code 557973639)  

 Powershell Err Msg             | No Output  

Run Summary : 11/26/25 09:01:57  
 Run Time                       | 14 seconds  

Error Summary : 11/26/25 09:01:57  
 Powershell Error               | 1  
 Fatal Error                    | 1