What is wrong with my Opera installing ? - Public key not available - 16.04
6809
How do I fix the GPG error "NO_PUBKEY"?
30130
Adding key to registry
39869
Mono Package for Wine is not installed
120661
Given a private SSH key, how do I recover my public key?
13231
What could be the reason, that private keys are not unlocked?
64509
Can't update from official repositories [Error 409]
137922
Why hasn't Trusty received the updates for OpenSSL's CVE-2016-2108 and CVE-2016-2107?
4653
How do I install wine?
21617
Why can't I press the Install button when installing applications from unknown sources?
14028
GPG Error while downloading software: "Clearsigned file isn't valid, got 'NODATA'"
70482
The key provided is not a valid Google API Key
127389
Problem with Vivaldi ppa
61948
ssh no longer allows public key authentication
48418
W: GPG error: http://ppa.launchpad.net precise Release: The following signatures couldn't be verified because the public key is not available:
11267
How to set a Compose Key in Ubuntu 18.04
135897
How do I install Flash in Opera?
5354
How do you add a certificate authority (CA) to Ubuntu?