Question: I'm getting the following error on running `sudo apt-get update` :

```
sudo apt-get update                                                                
Get:1 http://dl.google.com stable InRelease
100% [1 InRelease gpgv 3,435 B] [Connecting to in.archive.ubuntu.com] [ConnectiSplitting up /var/lib/apt/lists/partial/dl.google.com_linux_talkplugin_deb_dists_stable_InReleaseIgn 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 tried:

```
$ cd /var/lib/apt
$ sudo mv lists lists.old
$ sudo mkdir -p lists/partial
$ sudo apt-get update

```

But still getting the same error. Never faced this problem before. I was trying to install texlive-full and ran out of space during installation, `apt-get install` wasn't working then and gave the following output:

```
E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.

```

As per the answer here: [Message 'E:dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.'](https://askubuntu.com/questions/483611/message-edpkg-was-interrupted-you-must-manually-run-sudo-dpkg-configure-a) I tried:

```
cd /var/lib/dpkg/updates
sudo rm *
sudo apt-get update

```

And then this error occured. Now apt-get install is working fine but update isn't working. What is the solution?

Answer: 
On a hunch, I changed all references to `http://dl.google.com` to `https://dl.google.com` and it started to work. I think Google has shut down all their vanilla http ports and the just do a redirect to https. But apt and dpkg don't follow the redirects so they fail with 'NODATA' message.
Have you tried to run `sudo dpkg --configure -a` as recommended on that install output?

Also, after run it, I would recommend to run `sudo apt-get -f install` to fix any broken dependencies.