I tried to add the following instruction: |deb https://cran.r-project.org/ trsuty-backports main restricted universe| to: /etc/apt/sources.list When I updated my apt-get system I received an HttpError 404 Then I changed the address to: |deb https://cran.r-project.org/ trusty-backports main restricted universe receiving: HttpError 404 | |The address was taked from: https://cran.r-project.org/ Index |of /bin/linux/ubuntu || |What is the correct address to backports? sincerely hubabe | [[alternative HTML version deleted]]