Client: Missing Public Key for Ubuntu16.04

[JKawohl]

Expected behaviour

Install without error messages

Actual behaviour

Error Message:
W: GPG-Fehler: http://download.opensuse.org/repositories/isv:/ownCloud:/desktop/Ubuntu_16.04 Release: Die folgenden Signaturen konnten nicht überprüft werden, weil ihr öffentlicher Schlüssel nicht verfügbar ist: NO_PUBKEY 977C43A8BA684223
W: The repository 'http://download.opensuse.org/repositories/isv:/ownCloud:/desktop/Ubuntu_16.04 Release' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.

Steps to reproduce

1. Install owncloud-client from https://software.opensuse.org/download/package?project=isv:ownCloud:desktop&package=owncloud-client

2.
1.

Server configuration

Operating system:
Ubuntu 16.04

Client configuration

Client version: 2.2.2

Operating system:
Ubuntu 16.04
OS language:
German
Installation path of client:

Expected behaviour

Install without error messages

Actual behaviour

Error Message:
W: GPG-Fehler: http://download.opensuse.org/repositories/isv:/ownCloud:/desktop/Ubuntu_16.04 Release: Die folgenden Signaturen konnten nicht überprüft werden, weil ihr öffentlicher Schlüssel nicht verfügbar ist: NO_PUBKEY 977C43A8BA684223
W: The repository 'http://download.opensuse.org/repositories/isv:/ownCloud:/desktop/Ubuntu_16.04 Release' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.

Steps to reproduce

1. Install owncloud-client from https://software.opensuse.org/download/package?project=isv:ownCloud:desktop&package=owncloud-client

2.
1.

Server configuration

Operating system:
Ubuntu 16.04

Client configuration

Client version: 2.2.2

Operating system:
Ubuntu 16.04
OS language:
German

@jnweiger

[jnweiger]

Please follow the instructions on https://software.opensuse.org/download/package?project=isv:ownCloud:desktop&package=owncloud-client to install the public key:

"You can add the repository key to apt. Keep in mind that the owner of the key may distribute updates, packages and repositories that your system will trust (more information). To add the key, run:"

wget http://download.opensuse.org/repositories/isv:ownCloud:desktop/Ubuntu_16.04/Release.key
sudo apt-key add - < Release.key  

[jnweiger]

After installing the key like this, the error message from 'apt-get update' should go away.
'apt-get install owncloud-client' would still say

WARNING: The following packages cannot be authenticated!
  libqt5keychain1 libowncloudsync0 owncloud-client-l10n owncloud-client
Install these packages without verification? [y/N] n

This is an inconsistency in apt-get, it caches the earlier failure.
I see no workaround except say Y.

Maybe this is related to only having a weak 1024D/BA684223 key? I'd love to see a more accurate error message.

[sbigaret]

Same error observed on a fresh Ubuntu 16.04 install (the proper Release.key is installed, but 'apt-get install owncloud-client' still reports the same 4 un-authenticated packages jnweiger listed above).

[crrodriguez]

duplicate of https://github.com/owncloud/client/issues/5055

[dandv]

I see this problem on Ubuntu 16.04 after following all the installation steps, including adding the release key. sudo apt-get install owncloud-client shows:

WARNING: The following packages cannot be authenticated!
libqt5keychain1 libowncloudsync0 owncloud-client-l10n owncloud-client

@crrodriguez, you've marked this issue as a duplicate of a closed issue locked by @jnweiger. What's going on? Ubuntu is one of the most popular Unix distros, and this first encounter an Ubuntu user will have with OwnCloud is quite disappointing.