How To Fix Error 0x80240034 in Windows 10

The 0x80240034 error with Windows 10 is caused by Windows Update being unable to download the various files it requires to perform the updates that Windows requires.
The error is specifically known as the "WU_E_DOWNLOAD_FAILED" error, basically meaning that the system didn't download the correct "Windows Update" files.
The resulting issue means that your system is unable to manage the updates that are required to run, leading the system to exhibit erroneous behaviour.
To fix the problem, you essentially need to resolve any of the core issues preventing Windows Update from downloading the appropriate files - this comes in the form of having the ability to fix the likes of the Windows Update service, as well as being able to repair any of the underlying software applications integrating with Windows.
The message for the error will generally show as follows:
Failed to install - 0x80240034


The causes of the error will typically be:

• Internet connection issues
• Microsoft Update server errors / problems
• Error with the update payload itself
• Another miscellaneous error with the update (perhaps virus / third party software issue)
• The way to solve the error is to ensure that the various files Windows Update requires to 
• operate are working correctly. This can be done using the following steps:

1. Run Windows Update Troubleshooter

The first step is to run the Windows Update troubleshooter.
This is a tool bundled with Windows 10 (and I believe Windows 7) which allows you to clean up any of the issues that Windows may have with its underlying "update" processes.
To do this, you can use the following steps:

• Press "Windows" + "I" keys on your keyboard (loads up "settings")
• Click onto "Update & Security"
• On the left panel, select "Troubleshoot"
• From the list that appears, select "Windows Update"
• Click on "Run this troubleshooter"
• Let the process run
• After completion, restart your PC
• This probably won't fix the error, but should resolve the majority of issues that form with the update service.

2. Run SFC + DISM

After doing the above, you need to run the SFC + DISM commands.
These are small command-line based applications inside the Windows system, designed to provide users with the ability to clean up the majority of problems which form with Windows.
You can do this using the steps outlined here:

• Press "Windows" + "S" keys on your keyboard
• Type "CMD"
• On the first listing which shows, right-click and select "Run as Administrator"
• In the black box that appears, type the following commands:
• "SFC /scannow" + press "Enter"
• "DISM /Online /Cleanup-Image /RestoreHealth" + press "Enter"
• This will run a series of "scans" which will basically ensure that your system is able to run the various files / settings which it requires properly.
• Whilst this probably won't fix the problem (although it should for ~ 40% of cases), it should resolve a large number of underlying issues which may be leading it to show.

3. Manually Restart Windows Update Service

Next, you'll need to manually restart the Windows Update service.
This is a bit tricky, but should be the largest contributor to a solution.
Basically, the way Windows Update works is with what's known as a "service".
This ia an application which runs perpetually in the background of your system and allows a number of other processes to utilize it at will.
The Windows Update service is responsible for continually downloading, resuming and updating the various elements required to perform updates in Windows.
Unfortunately, it is often the case that the system will end up having problems with the service, which can be resolved by manually restarting it:
Press "Windows" + "S" keys on your keyboard
Type "CMD" and on the first item which appears, right-click and select "Run As Administrator"

• Into the black box which appears, type the following commands:
• 'net stop wuauserv' + 'Enter'
• 'net stop cryptSvc' + 'Enter'
• 'net stop bits' + 'Enter'
• 'net stop msiserver' + 'Enter'
• 'Ren C:\Windows\SoftwareDistribution SoftwareDistribution.old' + 'Enter'
• After doing this, you will need to start the various services again.This can be done using the following steps (again in the same CMD panel):
• 'net start wuauserv' + 'Enter'
• 'net start cryptSvc' + 'Enter'
• 'net start bits' + 'Enter'
• 'net start msiserver' + 'Enter'
• This should be followed by running the Windows Update "Check for updates" command again.

4. Temporarily Disable Firewall / Antivirus

Finally, one of the more common causes of the problem is a "false flag" from the likes of your antivirus or firewall application.
This happens because your system basically thinks that (for some reason) the Windows Update service is causing irregular (potentially harmful) Internet connectivity, and thus will block it.
To solve this, you can use the following steps:

• If you're using a THIRD PARTY antivirus
• Right-click on the security software's icon in the bottom-right of your Windows taskbar
• Select the equivalent of "pause" (it may be "Gaming mode" / "Temporarily Stop" etc)
• Select "10 Minutes" or the equivalent
• Try running Windows Update again
• If WU doesn't work at this point, try step 3 again with your antivirus temporarily disabled
• Restart your system after this attempt
• If you're using Windows Defender (default antivirus)
• Press "Windows" + "I" keys on your keyboard
• Select "Update & Security"
• From the left menu, select "Windows Security"
• Select "Virus & threat protection" so "Virus & threat protection settings"
• Switch "Real-time protection" to "Off"

Try updating the system, and if it doesn't work - try running step 3 again
After this, re-enable the Windows Defender service, restart your PC

If the above does not work, you'll probably have deeper issues with your system. Obviously, a generic Internet article isn't going to solve that.