I have latest stable version of Opera GX for both my laptop and android device. When I try to click on "connect a computer" on my android it shows a error page with the contents of this post's title. I have no idea why this is even a thing. By the way I have custom rom on my device and no Google Play Services. This is the only app that have such problem among hundreds of programs that I use.

@HemaBebo Thanks for reply. But i don't think this problem depends to which extension i want to install. I tried to install some extensions that i used before with opera browser but now it is not working anymore...

Not working anymore. (At least for me). I Have installed Opera Beta and it is up to date. When I try to open webstore it giving me an error and asks for refresh the page. No matter how much i try or how much time interval pass between tries it just doesn't work! (No "Available on Chrome" or "Add to Opera" buttons.) I Tried both with logging in to webstore and without logging in but none of them worked too. Please fix this issue...