Here’s my current /etc/yum.repos.d/katello.repo file:
# Place this file in your /etc/yum.repos.d/ directory
[katello]
name=Katello 4.15
baseurl=https://yum.theforeman.org/katello/4.15/katello/el9/$basearch/
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-foreman
enabled=1
gpgcheck=1
# Candlepin RPMs as supported by Katello - This is a coordinated
# copy of Candlepin's packages in order to ensure compatibility
[candlepin]
name=Candlepin: an open source entitlement management system.
baseurl=https://yum.theforeman.org/candlepin/4.4/el9/$basearch/
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-candlepin
enabled=1
gpgcheck=1
[pulpcore]
name=pulpcore: Fetch, Upload, Organize, and Distribute Software Packages.
baseurl=https://yum.theforeman.org/pulpcore/3.63/el9/$basearch/
gpgkey=https://yum.theforeman.org/pulpcore/3.63/GPG-RPM-KEY-pulpcore
enabled=1
gpgcheck=1
# source repositories
[katello-source]
name=Katello 4.15 Source
baseurl=https://yum.theforeman.org/katello/4.15/katello/el9/source/
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-foreman
enabled=0
gpgcheck=1
[candlepin-source]
name=Katello Candlepin source
baseurl=https://yum.theforeman.org/candlepin/4.15/el9/source/
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-candlepin
enabled=0
gpgcheck=1
[pulpcore-source]
name=pulpcore source
baseurl=https://yum.theforeman.org/pulpcore/3.63/el9/source/
gpgkey=https://yum.theforeman.org/pulpcore/3.63/GPG-RPM-KEY-pulpcore
enabled=0
gpgcheck=1
Looks like it has the correct pulpcore repo version (3.63) for Katello 4.15?
I did a bit more looking in this forum, and found this, which seems possibly relevant: Katello-nightly-rpm-pipeline 2155 failed - Infra & CI - TheForeman