Issue:

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!

Troubleshooting:

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.

Resolution:

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.