If you are looking for a way to fix an error code 0x80070057 that you are getting while installing Windows 10 Anniversary Update then you can try these below steps:
Go to Windows Update, by opening the start menu, search for ‘update’ and open “Check for Updates”. Now look down for Learn More and click on it, it should open a link on your default browser, Now click on ‘Get the Anniversary Update now’. File name should be ‘Windows10Upgrade28084’.
Open it and make sure it downloads the files. Watch for Verifying Download and make sure to turn off your Internet/WIFI/LAN if it reaches 100% IMMEDIATELY. Since you already have the error, file is already on your computer so it’s going to just verify like a hash check to make sure the Windows 10 update files are intact.
Now it should install upgrades but get stuck at the usual 2%, let it stay there for about 1 minute and re-enable your Internet/WIFI/LAN and the upgrade should finally pass 2%. In this way, you can easily fix this error and can continue with your installation process.
Hope it is helpful for you.