Strange Firefox Error?

I recently reinstalled my browser due to a virus; however, since my fresh install of the latest version of Mozilla - I can’t seem to even get the add-on to install. As soon as I get to the page where I am supposed to DL BTTV for Mozilla, I get this error. I’ve been looking for possible fixes, and through other threads but wasn’t able to find a thread similar to my problem, sorry if there actually is one out there. Thanks for your time and stuff.

You mentioned having virus issues. Have you installed any new security software? Try disabling it while you do the install…

This is caused by Avast. Avast is terrible internet security, and you should remove it. They’ve misflagged BetterTTV and prevent its install, and despite reaching out to them twice they’ve not responded.

Sweet, thanks for the help night. I disabled it and got it working.

this was the closest form i could find, i am also having problems i have allowed nightdev to install add-ons however firefox said that it cannot connect, is this due to a server problem or something else? i also use avast but i disabled after i read this report and still nothing. please help

Once you have disabled or uninstalled Avast, restart Firefox before retrying the download from