Windows Update Error 66a generally shows when you try and update the .NET framework of your PC. This is an important set of files which is used to power a lot of applications now, and is essential for many applications to run correctly on Windows. The error is caused by the Installer application for 66a not working properly – leading your computer to run much slower and with a lot of problems. To fix this issue, it’s recommended that you are able to fix the .NET installer, as well as then repair the various registry errors that Windows will have.
This error will typically show in this format:
Security Update for .NET Framework 4 on Windows XP, Windows Server 2003, Windows Vista, Windows 7, Windows Server 2008, Windows Server 2008 R2 for x64-based Systems (KB2160841)
Installation date: 12/6/2010 11:39 AM
Installation status: Failed
Error details: Code 66A
Update type: Important
What Causes Windows Update Error 66a?
- The .NET installer will be damaged / corrupt
- Windows will have problems with its settings
- Your PC will be outdated and have corrupted settings
How To Fix Windows Update Error 66a
Step 1 – Repair .NET Installation
Repairing .NET will allow your computer to run much smoother, by ensuring that this part of your system is not damaged or corrupted in any way. In order to fix this, we recommend using the steps outlined here:
- Click on Start and click on Control panel.
- Go to Program and Features.
- Scroll down to Microsoft.Net Framework 4 Client Profile, right click it.
- It will give you a choice of Uninstall/Change, click it.
- Then, it will give a choice to Repair it, pick Repair it. It will take about 4-10 minutes to repair (with my PC) your experience may vary.
- When completed, go to your update center, and update it again
Step 2 – Clean Out The Registry Of Your PC
The registry is another big cause of the Windows Update 66a error, as it’s where your computer will keep the important files, settings and options that Windows requires to run. If you’re experiencing problems with the registry of your PC, it’s highly recommended that you’re able to clean out any of the possible problems that this part of your system may have – by using a registry cleaner. This step is one of the easiest, and is one of the most important as well, as it will resolve any of the possible problems that this important part of your system may have.
We recommend downloading “RegAce System Suite 2.0” to fix the various problems that the registry will have inside your PC. This is an important registry cleaner tool that’s able to scan through your system and get rid of all the errors which it may have – allowing Windows to run much smoother as a result.