SQL Server Upgrade Advisor: Custom extensions or assemblies were detected on Report Server

You might see the following error when running SQL Server Upgrade Advisor on a SQL Server 2005/2008 instance.

Custom extensions or assemblies were detected on the Report Server.

Upgrade Advisor detected one or more custom data processing extensions on the Report Server. Upgrade can continue, but you must move the data processing extension assemblies to the new installation folder.

As the message indicates, this error simply means that you have custom extensions or assemblies on the Report Server you are upgrading. In most of the cases, you can resolve this by copying the custom extensions/assemblies from the “old” Reporting Services installation folder to the “upgraded” Reporting Services installation folder.

To give you a real example, I encountered this error when upgrading a SQL Server 2008 instance to SQL Server 2008 R2. The instance I was trying to upgrade had some Microsoft CRM Data Extension Assemblies as shown in the screen shot below. After the upgrade, I copied the DLLs to the new installation folder and everything was all set. 

Here are the paths to SQL Server 2008 and SQL Server 2008 R2 installation folders for Report Server.

\Program Files\Microsoft SQL Server\MSRS10.{InstanceID}\Reporting Services\ReportServer\Bin  ----- SQL Server 2008 Report Server

\Program Files\Microsoft SQL Server\MSRS10_50.{InstanceID}\Reporting Services\ReportServer\Bin ----- SQL Server 2008 R2 Report Server.