By default Windows 2008 R2 does not ship with the Twain DLLs installed but it is available via the optional Desktop Experience Pack.
Installing the Desktop Experience Pack optional component for Windows Server 2008 R2 will address this issue and enable scanning on Windows Server via TWAIN drivers dependent on STI support. TWAIN drivers with STI support that reference STI.inf from their driver installation INF file, and also TWAIN drivers that do not install the TWAIN Data Source Manager are expected to be affected by this change. If the Desktop Experience Pack is not installed, the driver installation will fail without explicit explanation. Additionally the device will have a yellow icon in the Devices and Printers folder. The Desktop Experience Pack can be installed through the following steps:
- Start Server Manager.
- In the details pane, locate the Features Summary area, and then click Add Features.
- In the Add Features Wizard, click to select the Desktop Experience check box, and then click Next.
- Click Install.
- After the Desktop Experience feature is installed, click Close to exit the Add Features Wizard, and then click Yes to restart the computer.