If when hovering over the upgrade icon on the taskbar you get:
Your version of Windows 10 would reach the end of service soon, Click to download a newer version of Windows 10 to stay supported.
or
An unsupported version of Windows will no longer receive software updates from Windows Update. These updates include security updates that can help protect your PC from harmful viruses, spyware, and other malicious software which can steal your personal information. Windows Update also installs the latest software updates to improve the reliability of Windows—such as new drivers for your hardware.
and you are unable to perform updates then this guide is for you. There are several things you can do to fix this issue presented here, it is advisable to follow them in a way how they are presented for best performance and system safety.
Download and run Setupdiag from the official MICROSOFT website. SetupDiag is a standalone diagnostic tool that can be used to obtain details about why a Windows 10 upgrade was unsuccessful. It works by examining Windows Setup log files to determine the root cause of a failure to update or upgrade the computer. Once the scan is completed, check the generated log files. The SetupDiagResults.log will be generated and saved in the same folder where you downloaded Setupdiag. Open SetupDiagResults.log using Notepad. You may need to take a look at these folders:
If there are any issues or conditions that are blocking the upgrade, they will be listed here.
Press ⊞ WINDOWS + R to open the run dialog
In run dialog type Regedit and press ENTER
Locate: HKLM\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate
Locate two DWORD files, if they do not exist, create them as:
TargetReleaseVersion
TargetReleaseVersionInfo
Set the value of TargetReleaseVersion to 1
If you are stuck on Windows 10 1909 and want to upgrade to Windows 10 20H2 now, you need to set the value for TargetReleaseVersionInfo to 20H2
Reboot the computer
Visit Microsoft.com and hit the ‘Update now’ button visible on the page
Download tool and run it
Click on Update now to start the upgrade process
“Windows Firewall and <Third party firewall name> Firewall are both turned off; tap or click to see available options”.This particular error could be caused by a lot of factors but when you manually check the firewall, you’ll find that there really is nothing wrong with both the Windows Firewall and the third party firewall. So if both the Windows Firewall and third-party firewalls like McAfee, Comodo, and many others are both turned off in Windows 10, then you need to do several things to resolve the problem – you need to check the supporting services that are required and uninstall and then reinstall the third party firewall on your computer. For more instructions, refer to the options provided below.
"An elevation of privilege vulnerability exists when the Windows Print Spooler service improperly performs privileged file operations. An attacker who successfully exploited this vulnerability could run arbitrary code with SYSTEM privileges. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights."