If you have a system with the Windows Vista operating system, you should understand that you are prone to being attacked by a multitude of error messages which could make it really hard to operate your computer normally.
The Windows update error 646 is pretty common and occurs when the computer is unable to install Windows updates.
This error happens mostly when you try starting the computer in the Safe Mode. The Windows firewall can be quite a nuisance because it could trigger this error in some cases.
It is obvious that this error appears when you have downloaded important Windows patches or updates and are trying to install them. At first glimpse, you would think that the files you have downloaded are corrupt. While this may rarely be the case, you will find that most often than not, the root of the problem is something else.
If in fact the files you downloaded are corrupt, it would bode you well to remove the files from your computer and your registry entries so that your computer is not affected. A corrupted registry is not a good thing to have on your computer – so it is advisable to get a registry cleaner and remove the bad registry headers.
To remove the 646 error, it is better to start the computer in the normal mode and update Windows manually instead of letting the Automatic updates run. Often manual installation is preferred by most users than automatic installation because manual processes give the user a greater degree of system control and flexibility.
If you insist on Automatic Windows update and have found that the Windows Firewall is the problem, it is advisable to turn off the Firewall from the Control Panel. After doing this, you can initiate the Windows update process again by starting it again. This has been known to help in a lot of cases.
The expert diagnosis is that the presence of the Wups2.dll file in the computer registry causes the error 646.
If you know your way around the registry, you can choose to do it manually; alternatively, you can use registry cleaner applications to do remove the file.