Windows 10 Update Error 0x80070020 occurs when users are upgrading the installed windows OS. So, if you're undergoing such issues then you may be able to communicate Windows support freely to urge cooperation. An accredited technician can assist you out. I'm sharing a link to at least one of these blogs, simply browse the online log and learn the procedure to work out this issue.
Run Windows Update Troubleshooter.
Disable your antivirus software or Windows Defender temporarily.
Restart Background Intelligent Transfer Service.
Run System File Checker or DISM scan.
Check and fix your hard disk errors.
Perform a clean boot.