When I try to update using apt-get update
give above error. I don't what causes this error, do you have any idea how can I fix this ?
W: GPG error: http://download.opensuse.org/repositories/home:/Horst3180/xUbuntu_16.04 Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 5A7D1D38BEB6D886 W:
The repository 'http://download.opensuse.org/repositories/home:/Horst3180/xUbuntu_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.