Plesk system updates fail: ERROR: failure: repodata/repomd.xml

Symptoms

System updates can not be installed on RHEL-based OSes via the Tools & Settings > System Updates menu:

Reason: 2022-01-12 03:36:22 INFO: pum is called with arguments: ['--list', '--repo-info', '--json']
2022-01-12 03:36:25 ERROR: failure: repodata/repomd.xml from PLESK_18_0_33-extras: [Errno 256] No more mirrors to try.
http://autoinstall.plesk.com/pool/PSA_18.0.33_5467/extras-rpm-CentOS-7-x86_64/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
2022-01-12 03:36:25 ERROR: Exited with returncode 1.

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Error: Unable to receive update information for the package(s)

Cause

The unavailable repository remains in /etc/yum.repos.d/ from previous Plesk Installer executions.

Resolution

1. Connect to the server via SSH.

2. Remove the plesk.repo file from /etc/yum.repos.d/ as it normally should be there only during Plesk Installer operations:

   # mv /etc/yum.repos.d/plesk.repo ~/

3. Re-run OS updates.