WebViewClient onReceivedError deprecated, new version does not detect all errors

You could also do following:

@SuppressWarnings("deprecation")
@Override
public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
    // Handle the error
}

@TargetApi(android.os.Build.VERSION_CODES.M)
@Override
public void onReceivedError(WebView view, WebResourceRequest req, WebResourceError rerr) {
    // Redirect to deprecated method, so you can use it in all SDK versions
    onReceivedError(view, rerr.getErrorCode(), rerr.getDescription().toString(), req.getUrl().toString());
}

Make sure you import android.annotation.TargetApi