24 Err:3 http://security.ubuntu.com/ubuntu cosmic-security Release
25 404 Not Found [IP: 91.189.88.149 80]
Switching from ubuntu 18.10 to the Long Term Support version 18.04 resolves it. According to this page, it's supported until 2025– I haven't tried newer versions yet.
If you receive the following error from Travis:
Switching from ubuntu 18.10 to the Long Term Support version 18.04 resolves it. According to this page, it's supported until 2025– I haven't tried newer versions yet.