I get the following lines when running :
sudo apt update
according to the instructions on this page:
https://nginx.org/en/linux_packages.html

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Err:10 http://nginx.org/packages/mainline/ubuntu tricia Release
404 Not Found [IP: 95.211.80.227 80]

E: The repository 'http://nginx.org/packages/mainline/ubuntu tricia Release' does not have a Release file.
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.
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Am I missing some understanding on following these instructions?