passenger: Ubuntu Bionic Apt repository does not have a Release file

Issue report

When following the instructions located at https://www.phusionpassenger.com/docs/advanced_guides/install_and_upgrade/standalone/install/oss/bionic.html to add the Apt repository to install Passenger on Ubuntu Bionic (18.04 LTS), an error message is displayed stating that the repository does not have a Release file, and that updating from such a repository is disabled.

Question 1: What is the problem?

Expected behavior: After following steps to import the PGP key and add the Apt repository, running apt update should check the repository without errors and allow packages to be installed from it.

Actual behavior: After importing the key and adding the repo, running apt update shows this error:

E: The repository ‘https://oss-binaries.phusionpassenger.com/apt/passenger bionic 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.

Question 2: Passenger version and integration mode:

Open source 5.0.30/Apache2

Question 3: OS or Linux distro, platform (including version):

Ubuntu 18.04 LTS (Bionic)

Question 4: Passenger installation method:

[x] Phusion APT repo