Cannot install update (KB2538243) - Error 0x80070643

Protector, just let the OP see if it installs on Windows 10.

Thanks for the help but after I had downloaded the update and tried to install it, it failed and said "another installation is already in progress, complete that installation before proceeding"
Windows update has found this update for me, I am running Windows 10 Pro 64bit.

pw2112 said:

Thanks for the help but after I had downloaded the update and tried to install it, it failed and said "another installation is already in progress, complete that installation before proceeding"
Windows update has found this update for me, I am running Windows 10 Pro 64bit.

Try to restart your computer.

I have restarted my pc, but it made no difference, the update is still there and still fails to install, giving the same error code.
I'm concerned that until this one installs I won't get any more updates, is that how it works?

I have some solutions for

"another installation is already in progress"

1. "Select Services, right click on Windows Installer in the list and select Properties. If you’re having the problem, the Windows Installer service is started, and the Stop button is disabled. Simply rebooting doesn’t stop the service. Here’s how you stop it. In the Properties dialog, change Startup type to “Disabled”, click OK, and reboot your computer. This stops the service. After your computer reboots, again open Computer Management (right-click on Computer and select Manage), open Windows Installer Properties, and change the Startup type back to Manual. Now you’re good to go and can start a new installation."

2.(very easy) Open Task Manager (Ctrl+Alt+Delete or right click on taskbar and click Start Task Manager). Go to process named msiexec.exe and click End Task. Now, start the installation and check.

3.Look in the STARTUP Tab of Taskmanager for any kind of installer that is set to load at Startup...
If you find one, disable it.

Do the same thing in System Configuration (MSCONFIG) Services Tab....
Check the box to hide all Microsoft services and check out what is left...( It's probably a 3rd Party, but maybe not)...

Uncheck the box for anything suspicious... You may be surprised by some of the unnecessary stuff you find...

OK, an update. I found the process "msiexec" it was called installer. I clicked end task and ran the update again. It worked!
A big thank you to everyone who posted to try and help and especially Hexagon12 for their solution that solved my problem

After WEEKS of trying to fix this error, I came upon a simple solution.
Link to https://www.microsoft.com/en-in/soft...load/windows10 then click on the first button
"Update Now".
I was worried I would lose my desktop and installed programs, but provided you check "Keep Files and Settings" then you will receive the latest Windows update cleanly installed, with all programs and desktop remaining the same and all errors encountered either during Windows Update or during program installations a thing of the past.
Such an easy resolution, rather than messing around with re-installing .NET frameworks or C++ libraries or making changes to the registry etc.