I do not know a whole lot about how to fix this , but a popup opens with every website i open to sell some other item/s. i have Avast Virus and have for years. But somehow this one has gotten thru, How do I get rid of it?
A Screenshot of the Avast Alert with the See Details option selected might help.
e.g. the site being blocked ?
Is this always going to a different site to that you were visiting ?
However, I suspect it is something in either your browser cache or an updated or new add-on.
What browser are you using ?
Starts by clearing your browser cache and cookies, including 3rd party cookies and restart your browser.
If that resolves it you should be good to go.
If it doesn’t try running your browser with add-ons disabled.
If that resolves it, have you added or updated any add-ons ?
If so try disabling that add-on - and restart and try again.