Fix Windows Vista 80070490 Error during SP2 Installation

If you are installing Windows Vista Service Pack 2 (SP2) or Windows Server 2008 Service Pack 2, you may have faced error of code “80070490” while running it. The problem can occur even when you do Automatic Update of Windows. The full error message in Windows Update panel is “Windows could not search for new updates. Code 80070490 Windows Update encountered an unknown error.”

Microsoft in it’s KB976920 has released a free tool to resolve this failed installations. It’s called System Update Readiness Tool (KB947821). This tool can be used to fix any update issues.
Step 1: Download System Update Readiness Tool (Checksur.exe) from Microsoft Site. Make sure you choose the one for your Operating System.

For x86-based versions of Windows Vista and of Windows Server 2008: Download the Windows6.0-KB947821-v5-x86.msu package now.

For x64-based versions of Windows Vista and of Windows Server 2008: Download the Windows6.0-KB947821-v5-x64.msu package now.

For IA64-based version of Windows Vista and of Windows Server 2008: Download the Windows6.0-KB947821-v5-ia64.msu package now.

Step 2: Run the downloaded Checksur.exe tool. The tool will run a onetime scan for inconsistencies that cause any update failures in future.
Step 3: After the scan is complete, you can go ahead and install SP2 or any updates.