When i want to buy something appears a error mesage that says I have to set the trade url
but it dont let me, when i click save(or update in preferences page) the page just reloads without saving the url

please help!

Possible reasons:
1. Your account is not eligible for using trade offer.
2. Your backpack is private.

If not any of above, you could try to get a new trade offer URL.

i get same problem too, many my buyer cannot trade with bot, every time bot said trade offer invalid. when i check, it can ( i even remove friend for try that trade offer link)

i also try send my bot my trade offer link, and same thing happen. it really weird, since i can grab my bot stuff easly, but cannot trade in normal way.

I have the same problem, Is there a solution?

Same problem here