If your Windows Update error code displays as 0x800B0109, which means that you have an issue with a device driver.
Error Code 0x800b0109 is common for all the Windows Operating systems when you try to install the updates. It usually appears when Windows 10 or Windows 7 update system is broken or there is network related glitches.
Usual causes for this Error Code 0x800b0109 are communication failure over the Internet with Microsoft update servers.
Firstly, I will suggest you to do Windows Troubleshoot for Error Code 0x800b0109.