The DLLs that are listed in the report define extended stored procedures that have not been registered using the full path. ...

The DLLs that are listed in the report define extended stored procedures that have not been registered using the full path.  These extended stored procedures will not work after upgrade because SQL Server will be unable to locate the DLLs. Use sp_dropextendedproc and sp_addextendedproc to drop and then reregister the DLLs with the full path.