The addon of this link https://addons.mozilla.org/en-US/firefox...
is not working (for me) and gives the same message as if I were to click on the link of the DDG search page. But the post on the above page led me to the
DuckDuckGo Plus 0.4.2 at https://addons.mozilla.org/en-US/firefox...
and this installed and replace Google.
I hope this helps.
https://addons.mozilla.org/en-US/firefox...
is not working (for me) and gives the same message as if I were to click on the link of the DDG search page. But the post on the above page led me to the
DuckDuckGo Plus 0.4.2 at
https://addons.mozilla.org/en-US/firefox...
and this installed and replace Google.
I hope this helps.