Updating apt get
Additionally, Windows does not easily allow overwriting of in-use executables so installing a new version of the Cygwin DLL while a package manager is using the DLL is problematic. This will install an enormous number of packages that you will never use, including debuginfo and source for every package.If you really must do this, clicking on the "Default" label next to the "All" category to change it to "Install" will mark every Cygwin package for installation.After installation, Linux requires configuration and systems administration.
Some examples: One highly unlikely, but occasionally possible, cause for this error is if having added the same key twice with different expiry dates.
You would likely know having done so for this answer to be relevant to you.
This can happen, as it did for me, when hosting your own repository with your own keys.
List All Installed Packages with apt on Ubuntu, step by step tutorial.
Apt is a command-line interface that allows you to perform actions such as installing new software packages, removing unnecessary software packages, updating the existing software packages, searching for specific software packages etc.