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幾個月前，我已經停止爲我的KUbuntu 14.04接收Oracle JDK的更新。 我照着http://www.webupd8.org/2012/09/install-oracle-java-8-in-ubuntu-via-ppa.html 它的工作裝和以前配置的，但現在更新過程中我只看到錯誤：如何恢復Oracle JDK更新？
Err https://ppa.launchpad.net trusty/main amd64 Packages
gnutls_handshake() warning: The server name sent was not recognized
Err https://ppa.launchpad.net trusty/main i386 Packages
gnutls_handshake() warning: The server name sent was not recognized
W: Failed to fetch https://ppa.launchpad.net/webupd8team/java/ubuntu/dists/trusty/main/binary-amd64/Packages gnutls_handshake() warning: The server name sent was not recognized
W: Failed to fetch https://ppa.launchpad.net/webupd8team/java/ubuntu/dists/trusty/main/binary-i386/Packages gnutls_handshake() warning: The server name sent was not recognized
E: Some index files failed to download. They have been ignored, or old ones used instead.
我當前安裝的Java版本爲1.8.0_91。的/etc/apt/sources.list.d/webupd8team-java-trusty.list
內容：
deb https://ppa.launchpad.net/webupd8team/java/ubuntu trusty main
請幫我解決這個錯誤。