Google has provided more details and steps for updating Android System WebView and Google Chrome as well as how to manually update WebView or Chrome if the update of either app fails to complete.
https://support.google.com/android/thread/103561027?hl=en“To resolve this issue, Android System WebView and Google Chrome need to be updated. Google Play will soon download the update to these apps on affected devices, or you can update manually to resolve the issue immediately. Some devices do not have WebView pre-installed and only need to update Chrome.
To manually update Android System WebView and Google Chrome right now:
Open the Play Store app.Search for “Android System WebView.”Select Update. If it doesn't say “Update”, skip this step.Repeat these steps for Google Chrome”