🎉
Ubuntu16.04から18.04のupgradeに"No new release found."
事象：
$ sudo do-release-upgrade
Checking for a new Ubuntu release
No new release found.
->解決していきましょう！
原因特定
- 念のために、release upgraderのPromptがltsであることを確認します。
$ cat /etc/update-manager/release-upgrades
# Default behavior for the release upgrader.
[DEFAULT]
# Default prompting behavior, valid options:
#
# never - Never check for a new release.
# normal - Check to see if a new release is available. If more than one new
# release is found, the release upgrader will attempt to upgrade to
# the release that immediately succeeds the currently-running
# release.
# lts - Check to see if a new LTS release is available. The upgrader
# will attempt to upgrade to the first LTS release available after
# the currently-running one. Note that this option should not be
# used if the currently-running release is not itself an LTS
# release, since in that case the upgrader won't be able to
# determine if a newer release is available.
Prompt=lts
->問題なし。
- do-release-upgradeをデバッグモードで実行します。
$ sudo DEBUG_UPDATE_MANAGER=1 do-release-upgrade
Checking for a new Ubuntu release
MetaRelease.__init__() useDevel=False useProposed=False
/etc/update-manager/meta-release: https://changelogs.ubuntu.com/meta-release
/etc/update-manager/meta-release: https://changelogs.ubuntu.com/meta-release-lts
/etc/update-manager/meta-release: -development
/etc/update-manager/meta-release: -proposed
metarelease-uri: https://changelogs.ubuntu.com/meta-release-lts
MetaRelease.download()
result of meta-release download: '<urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)>'
NO self.metarelease_information
No new release found.
->認証エラーらしいです。
解決方法：
$ sudo SSL_CERT_FILE=/etc/ssl/certs/ca-certificates.crt do-release-upgrade
->よし、upgradeできるようになりました。
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