Total Commander

you must use an external browser.

And that is what I have been doing for a long time - but suddenly the plugin could not find the default (Chrome) browser...

Strange, I'm just passing the URL as an intent to Android, and Android should then show an app picker dialog with available browsers.

Well, as I wrote, deleting and reinstalling the app fixed the problem. First I tried just deleting the app's data and cache, but that was not enough.