apt updateを実行すると以下のエラーが発生．
E: Failed to fetch https://packagecloud.io/slacktechnologies/slack/debian/dists/jessie/InRelease 402 Payment Required [IP: 54.183.38.243 443] E: The repository 'https://packagecloud.io/slacktechnologies/slack/debian jessie InRelease' is no longer signed. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.
この情報に従ってみた(OSとDistributionについてはこれを参考にubuntu,focalにした)けど，依然として同じエラーメッセージが出る．
wget https://packagecloud.io/install/repositories/slacktechnologies/slack/script.deb.sh chmod +x script.deb.sh sudo os=ubuntu dist=focal ./script.deb.sh Checking for curl... Detected curl... Checking for gpg... Detected gpg... Running apt-get update... done. Installing apt-transport-https... done. Installing /etc/apt/sources.list.d/slacktechnologies_slack.list...done. Importing packagecloud gpg key... done. Running apt-get update... done. The repository is setup! You can now install packages.
Software & Update > Other Software からslack関係のレポジトリのチェック(ubuntu/focalとdebian/jessie)を全て外したらエラーがでなくなった． この対応が正しい対応なのか謎なのが怖い．．．
