After an In-Place upgrade of Active Roles, the following is observed in the Configuration Center after being prompted to upgrade the Web Interface sites configuration:
Unable to retrieve Web Interface site configuration objects.
Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: Index
The sites function normally, but the Configuration Center repeatedly prompts for upgrades.
Clear the IsInPlaceUpgrade flag in the Registry.
Restart the Configuration Center to verify issue resolution.