apt-get update get GPG error running Ubuntu 14.04 in VMWare

Question

I am currently on Ubuntu 14.04 in VMware Workstation12. I tried install cmake 3.6.2 at first, while I get the error

Could NOT find CURL (missing: CURL_LIBRARY CURL_INCLUDE_DIR)

Then I searched it on the Internet, get this answer http://www.cnblogs.com/suyuan1573/p/4251389.html, when run sudo apt-get upgrade, get

E: GPG error: http://ubuntu.cn99.com precise InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)

I looked into multiple solution on the Internet including these

• How to fix GPG error/BADSIG while running apt-get update?

• getting GPG error while runnign "sudo apt-get update" command, and

• How to fix GPG error/BADSIG while running apt-get update?.

All doesn't work for me.

How to solve the problem? Thanks, allanna.

I don't wanna re-install Ubuntu, now I can't install any software. When I type apt-get update, I get E: GPG error: http://ubuntu.cn99.com precise InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)

Answer 1

It's about proxy problem. I altered the proxy links. Firstly backup the proxy list:

sudo cp /etc/apt/sources.list /etc/apt/sources.list_backup

Then open sources.list with gedit or other editor:

sudo gedit /etc/apt/sources.list

Choose the approxiate list for u, I'm in China, this works well:

deb http://mirrors.163.com/ubuntu/ trusty main restricted universe multiverse

ps: delete the original list

Finally, run

sudo apt-get upadate