apt-get update "signatures were invalid" error
6105
What is the easiest way to resolve apt-get BADSIG GPG errors?
16578
How to upgrade a single package using apt-get?
30068
Update: Failed to lock /var/cache/apt/archives/lock
96696
timeout errors in apt-get update/install
21184
Running "sudo apt-get update" returns connection errors
126538
Ubuntu 12.04 GPG error: http://archive.ubuntu.com precise Release: The following signatures were invalid: NODATA 1 NODATA 2
17596
Invalid signature for Kali Linux repositories : "The following signatures were invalid: EXPKEYSIG ED444FF07D8D0BF6 Kali Linux Repository"
48418
W: GPG error: http://ppa.launchpad.net precise Release: The following signatures couldn't be verified because the public key is not available:
28650
`apt-get update` cannot find Ubuntu servers
80899
"no public key available" on apt-get update
73173
How to Fix Broken Packages?
93246
How to resolve conflicting distributions in apt-get
127196
"Error processing package" - apt upgrade cannot run due to package configuration errors
84309
How to resolve E: Internal Error when using apt-get remove?
15413
sudo apt update always giving Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?)
119273
Code Sign error: a valid provisioning profile matching the application's Identifier ... could not be found
135383
Unable to update my system Ubuntu13.04: Getting message - requires installation of untrusted packages