Here is what I see in my terminal:

```
user@user-OptiPlex-9020:~$ sudo apt-get update
Ign http://extras.ubuntu.com trusty InRelease                                  
Ign http://in.archive.ubuntu.com trusty InRelease                              
Get:1 http://dl.google.com stable InRelease                                    
100% [1 InRelease gpgv 1,661 B] [Connecting to 192.168.0.90 (192.168.0.90)] [WaSplitting up /var/lib/apt/lists/partial/dl.google.com_linux_chrome_deb_dists_stable_InRelease intoIgn http://dl.google.com stable InRelease                                      
E: GPG error: http://dl.google.com stable InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)

```

I have the required authentication information in /etc/apt/apt.conf file:

```
Acquire::http::proxy "http://username:password@192.168.0.90:8080/";
Acquire::https::proxy "https://username:password@192.168.0.90:8080/";
Acquire::ftp::proxy "ftp://username:password@192.168.20.0:8080/";

```

I am not able to figure out the problem.