This is an update error that can be quite irritating as it prevents you from installing the newest Windows 10 version.
Error 0x80070020 is a common error with Windows update that occurs while you are trying to upgrade Windows system.
Turn off – Active Antivirus software
There are chances when any third party antivirus software may cause problems while downloading Windows update. This occurs when your OS doesn’t support the installed antivirus/system security software.
This conflict can also harm other Windows features, which includes Windows Update process too.

So, it is better to disable you antivirus software and then start with the update process.
Once you install and download Windows 10 update, enable the antivirus program again.
Try – Post Restarting BITS service
Press Windows + R to open -Run Dialogue box and type –msc, now press enter.
You will see a window displayed where look for -Background Intelligent Transfer Service and then right-click it.
Select-Properties and then open – General
Search for –Startup Type and then select accordingly
In case Background Intelligent Transfer Service (BITS) process doesn’t start in running mode then just right-click it and then select
Finally, save changes and then close- Services window.
Run – SFC/SCANNOW
SFC or SYSTEM FILE CHECKER is the inbuilt tool found in Windows system. It helps you handle the windows update issue. The tool helps scan your system for errors or corrupted features and then also repair it smoothly.
Open – command prompt with admin
Open – Start Menu and then right click –Command Prompt—Select Run as administrator.
Once you open command line, type – sfc/scannow
The command takes a couple of minutes to scan the system
Once the scanning is complete close command prompt
Run – inbuilt Windows Update Troubleshooter
To utilize Windows update troubleshooter, download the tool by visiting the official site of Microsoft and download from the link. Once you download the tool run it .
Just follow the instructions you get on your screen.
In case of any errors detected by the tool then it will solve the errors automatically.
RUN – CHKDSK
You need to run – CHKDSK command which helps you repair the bad sectors resulting in error 0x80070020 or other Windows errors.
Open – Start Menu, right click –Command Prompt—Select Run as administrator.
Click – “Yes” to expand.
Next, type chkdsk and “C“, present in system drive.
Press –ENTER in order to run the command.
Ensure that system is free of ERROR and MALWARE
If your system is filled with malware, virus or any system error then you will not be able to continue with downloading Microsoft updates.
So, make sure that you keep your system free of malware or any other error. You cannot actually accomplish the task manually so you can opt for a professional tool to fix PC errors. Make sure you scan your system completely often to avoid malware or virus attacks.