sudo apt-get update not connecting to repositories - GPG signature invalid / repository has no release file
6105
What is the easiest way to resolve apt-get BADSIG GPG errors?
103929
sudo apt upgrade error 18.04 (Broken Packages)
14028
GPG Error while downloading software: "Clearsigned file isn't valid, got 'NODATA'"
63320
Ubuntu repository does not have a Release file
28000
"GPG error:The following signatures were invalid: KEYEXPIRED"
117728
sudo apt update error
75879
How do I get add-apt-repository to work through a proxy?
76241
"no public key available" while upgrading using update-manager
113145
What does 'apt-get install update' do?
126538
Ubuntu 12.04 GPG error: http://archive.ubuntu.com precise Release: The following signatures were invalid: NODATA 1 NODATA 2
339
How to resolve "Failed to download repository information"?
82035
Debian: The repository does not have a Release file
154420
"Failed to download repository information" error
116445
"Can't check signature: public key not found" while upgrading, why?
96696
timeout errors in apt-get update/install
58759
How to fix missing GPG keys?
112568
Cannot remove a repository that complains it has no public key