Cannot navigate to file:// URIs

Hi, will appreciate some help with next issue:
I try to navigate to next local URL:

let completeUrl = "file:///C:/Program%20Files/about.html";

const szRunOptions = "--start-maximized --ignore-certificate-errors --disable-web-security --disable-site-isolation-trials --allow-file-access-from-files --disable-popup-blocking --file-url-path-alias --custom-devtools-frontend --user-data-dir=" + szTempFolder;

Browsers.Item(AppSettings.settings.testSettings.browserType).RunOptions = szRunOptions;

Problem: the URL is not even written in the browser address, as a result the web page is not opened.

Thank you in advance,

Michael