Windows like any operating system sometimes has bugs and errors. The system has been designed to have automatic and sometimes scheduled updates. However, it happens that the installation of the downloaded patches presents an error and usually it has the code 66a. In this article we will see how to fix this error of the update manager.

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Some concepts of the error message

Here are some definitions of the words in your error, to help you understand your problem:

  • Error Code: An error code is a value returned to provide context as to why an error occurred
  • Windows: GENERAL SUPPORT FOR WINDOWS
  • Windows Update (WU): A service offered by Microsoft that provides updates for the operating system.
  • Framework: A framework is an existing library or set of libraries that provides a global application structure. This is so that the developer can focus primarily on the implementation details of his application.

Why the 66a error?


The .NET Framework is a technology that supports the creation and execution of Windows applications and web services. In other words, it is the essential element for the operation of many software products developed with Microsoft .NET. Of course, all the software downloaded from Windows Update is part of it. For Windows programmers, it uses the .NET Framework environment to ensure that their final software will run smoothly. Only, it’s hard to think of perfect software without errors; so therein lies the problem.

Windows Update error 66a usually occurs when the .NET Framework fails to start up or crashes while running. This type of error appears as an annoying notification on your screen or is the message displayed in detail when an update installation fails.

Causes of Windows 66a update error code

Windows programmers try to anticipate errors and correct many of them during testing, but an unrunnable update is not the only cause. Errors can also come from runtime incompatibility in parallel applications. In other words, there are applications that could block the action of the .NET Framework during the update installation phase. Another cause could be a memory problem, where the buffer space has been overflowed and the newly acquired data cannot be processed properly. Finally, the possibility of a virus infection should not be overlooked, as it is well known that viruses modify the operation of system software.

Runtime errors can be annoying and persistent, but it is not totally hopeless, repairs are possible. Here are some methods to fix it.

Method 1: Close conflicting programs


When you get an error like this, keep in mind that there might be a program that doesn’t allow itself to be run at the same time as the .NET Framework. This is rarely the case, but it is not to be neglected. You should therefore visit the pages of the software you use to find out if they are incompatible with Windows libraries. Then, you will only have to stop them normally or through the task manager.

Method 2: Update the program

In case the update from Windows Update brings you an error, run a scan again to see if another version is available to solve the problem. If not, you will simply have to do it manually by visiting the official website of the publisher to get the latest version.

Method 3: Reinstall the runtime libraries


As we said, the .NET Framework is the software that you can do without on Windows. In case the previous solutions did not bear fruit, you will have to reinstall the whole package. To do this, you open the control panel, then Programs and Features and finally make a right click on ‘Microsoft .NET Framework 4’. Select ‘Uninstall/Modify’; from there you can first attempt a repair even if in 60% of cases it is a failure. Otherwise uninstall directly the program that you will download directly from the Microsoft site.

Method 4: Update your antivirus protection and scan your PC completely

In the case of a virus infection, your antivirus is the easiest way to find the agent that disturbs the system. If the virus is customized, complex and rare, it will be difficult for you to know what it was doing to your computer. Nevertheless, you will have already eliminated one annoying factor from the equation. After that a full system file recovery is sometimes advisable, because even if the virus is neutralized, your files are lost.

Windows Update error 66a very often comes from a problem in the Windows Framework in charge of running software. Solving the issue does not require being a genius in anything fortunately. All the possible solutions contribute to the correct installation of the blocked software without making any major changes. It would be nice to know also that in the worst case, reinstalling the system with a recent version could solve the problem. You just need to measure the extent of it and backup all your data before that.

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