Avast and malwarebytes logs are clear.
I've already tried the following steps but windows defender is still turned off, and windows update is not updating:
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Method 1:
I would suggest you to place the computer in Clean boot state and then try to install the updates.
Clean boot: To help troubleshoot error messages and other issues, you can start Windows by using a minimal set of drivers and startup programs. This kind of startup is known as a "clean boot." A clean boot helps eliminate software conflicts. Here is the link for your reference to perform clean boot.
http://support.microsoft.com/kb/929135
Note: Please go through the section: How to reset the computer to start as usual after troubleshooting with clean boot of the Kb article to boot the computer in normal startup after fixing the issue.
Method 2:
I would suggest you to run System Update Readiness Tool and check. Refer to the link to do so.
System Update Readiness Tool fixes Windows Update errors in Windows 8, Windows 7, Windows Vista, Windows Server 2008 R2, and Windows Server 2008
http://support.microsoft.com/kb/947821
Note: Refer to the section Windows 8
Method 3:
Method 1:
I would suggest you to place the computer in Clean boot state and then try to install the updates.
Clean boot: To help troubleshoot error messages and other issues, you can start Windows by using a minimal set of drivers and startup programs. This kind of startup is known as a "clean boot." A clean boot helps eliminate software conflicts. Here is the link for your reference to perform clean boot.
http://support.microsoft.com/kb/929135
Note: Please go through the section: How to reset the computer to start as usual after troubleshooting with clean boot of the Kb article to boot the computer in normal startup after fixing the issue.
Method 2:
I would suggest you to run System Update Readiness Tool and check. Refer to the link to do so.
System Update Readiness Tool fixes Windows Update errors in Windows 8, Windows 7, Windows Vista, Windows Server 2008 R2, and Windows Server 2008
http://support.microsoft.com/kb/947821
Note: Refer to the section Windows 8
Method 3:
I would suggest you to disable the third party anti-virus temporarily, if you have installed any, and check.
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Thank you for you attention!
Mauro