Move User from Online to Server Fails


When trying to move a user from Skype for Business Online to Skype for Business Server, the following error was being output in the Skype for Business Server Control Panel – “Index was outside the bounds of the array” – not the most helpful issue to troubleshoot!


A customer had recently requested support for the migration to SfB Online to SfB Server for a subset of users.

After initially understanding why this migration scenario was taking place, I began to look at the configuration in its entirety:

  • All Skype for Business Servers were running the latest CU
  • The SfB Server Topology was correctly and successfully published with no warnings or errors
  • All firewall ports had been opened correctly
  • Public DNS was pointing to the on-premise estate, for all required records
  • A Shared SIP Address space had been enabled
  • The Skype for Business control panel Hybrid wizard confirmed “all prerequisites had been met”

When testing a move of a user myself, I too encountered the error the customer had been reporting, which was;

“Index was outside the bounds of the array” – not the most helpful issue to troubleshoot!

The same occurred too when trying to move a user using PowerShell, with the appropriate switches.

As we had not implemented the solution, it was time to take a step back and look at all “moving components” within this scenario, including AAD Connect and ADFS.


When viewing the attributes that were being synchronised from the customers AD to Azure AD, I noticed that none of the MS-RTC* Attributes were included… hmmmm…..

After speaking with the customer, I then determined that Skype for Business Server had been install AFTER the installation of AAD Connect!

We decided to “Refresh the Directory Schema” using the AAD Connect Wizard, o ensure that our SfB attributes were being synced.

Following on from the refresh, we could then complete the procedure of moving a user from Online to Server, for those that needed to be migrated.