Error is occurring when trying to configure SSRS Database Setup from the Reporting Service Configuration Manager. Following is the error you get.
The database version (C.0.8.40) does not match your reporting services installation. You must upgrade your reporting services database.
Couldn't generate the upgrade script. There is no upgrade script available for this version.
Error is occurring when it can't match with the database version of your reporting service installation. This is happening when you install you components in following order.
1. Install SQL Server 2005 Database Services.
2. Install SQL Server 2005 Service Pack 3.
3. Install SQL Server Reporting Services.
Because of this, SQL Server Report Services and Database Services versions are mismatching. Therefore, you need to install SQL Server Service Pack 3again so that both versions are equal.