GitHub automatically deletes inactive SSH keys to help keep accounts safe, such as after someone leaves a job or loses a computer.
You can check if you haven't used an SSH key in a year by reviewing your account's security log. For more information, see "Reviewing your security log."
After your inactive SSH key is deleted, you must generate a new SSH key and associate it with your account. For more information, see "Generating a new SSH key and adding it to the ssh-agent" and "Adding a new SSH key to your GitHub account."

Formed in 2009, the Archive Team (not to be confused with the archive.org Archive-It Team) is a rogue archivist collective dedicated to saving copies of rapidly dying or deleted websites for the sake of history and digital heritage. The group is 100% composed of volunteers and interested parties, and has expanded into a large amount of related projects for saving online and digital history.
