Virtual directories are unspecified
Upgrade Advisor did not detect virtual directory settings for the Report Server Web service or Report Manager. After upgrade completes, you must configure URL reservations for the report server by using the Reporting Services Configuration tool.
Upgrading a Reporting Services installation includes reserving new URLs for the Report Server Web service and Report Manager. Upgrade Advisor did not detect virtual directories for the report server or Report Manager for the instance to be upgraded, and therefore the upgrade process has insufficient information to create URL reservations for the upgraded report server. Upgrade can continue, but the report server or Report Manager virtual directory will be undefined after the upgraded installation.
After upgrade finishes, use the Reporting Services Configuration tool to set the URLs for report server and Report Manager. Use IIS Manager to remove any virtual directories you no longer need.
For more information, search for "How to: Configure a URL (Reporting Services)" in SQL Server Books Online.