New answers tagged software-sources
It seems to be a problem with your software sources. Press Alt+f2 on your keyboard and write following code software-properties-gtk Then in the Ubuntu Software tab change the Download from setting. Change to Main Server if using any local server. See if it works. If the above answer doesn't solve the error, open a terminal and run following code ...
This is caused by some proxy packages like anon_proxy, it passes all of HTTP connections through a local proxy using an environment variable. So, to change this edit /etc/environment and comment out HTTP_PROXY and http_proxy in last two lines.
According to a Launchpad bug page, it needs a sponsor to upload it to the Ubuntu and Debian repositories. I read down the thread a bit and, while its rather old, it seems the developer still has no sponsor.
just add http:// edit it like this deb http://download.virtualbox.org/virtualbox/debian trusty contrib non-free then sudo apt-get update and if that doesn't fix which it should then just delete the file from the sources.list.d directory dont worry it wont effect anything.
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