При обновление системы apt update выдает следующую ошибку.
Ign:3 https://attic.owncloud.org/download/repositories/10.0/Ubuntu_18.04 InRelease
Get:7 https://attic.owncloud.org/download/repositories/10.0/Ubuntu_18.04 Release [984 B]
Get:8 https://attic.owncloud.org/download/repositories/10.0/Ubuntu_18.04 Release.gpg [481 B]
Err:8 https://attic.owncloud.org/download/repositories/10.0/Ubuntu_18.04 Release.gpg
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 47AE7F72479BC94B
Fetched 252 kB in 2s (130 kB/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
30 packages can be upgraded. Run 'apt list --upgradable' to see them.
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://attic.owncloud.org/download/repositories/10.0/Ubuntu_18.04 Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 47AE7F72479BC94B
W: Failed to fetch http://download.owncloud.org/download/repositories/10.0/Ubuntu_18.04/Release.gpg The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 47AE7F72479BC94B
W: Some index files failed to download. They have been ignored, or old ones used instead.
Из ошибки видно что ключа не существует.
Смотрим следующую версию 10.1 при ручной проверке ключ доступен.
curl https://attic.owncloud.org/download/repositories/10.1/Ubuntu_18.04/Release.key
Добавим новый путь в sourcelist.
sudo vim /etc/apt/sources.list.d/owncloud.list
deb https://attic.owncloud.org/download/repositories/10.1/Ubuntu_18.04/ /
Добавим ключ.
sudo apt-key adv --fetch-keys
https://attic.owncloud.org/download/repositories/10.1/Ubuntu_18.04/Release.key
Обновим систему.
sudo apt update
sudo apt upgrade
Запуск процедуры обновления owncloud.
sudo -u www-data php occ upgrade
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