Remote debugging firefox on Android

Question

I'm trying to debug remotely from firefox 68.6, on Android 4.4.2 but i can't enable wifi debug because it says that need a QR reader app (see image below for more detail, there is a link because I can't embed a image for the low reputation). I tried different QR code app, but none of them changed the situation. How can I enable this option?

Of course if I try to connect from desktop now, it says Connection failed.

I refer to this option at the bottom of the page here

Answer 1

Firefox requires a specific QR code scanner app – com.google.zxing.client.android – which is silly and not very well documented. This functionality was removed some time between Firefox 68 and 80.

• ZXing "Barcode Scanner" App on Play Store
• Offending source code (no longer present)
• Sort-of related bug