Patching of clients using SUSE Manager fails with error 404

E: Failed to fetch https://suma.fqdn:443/rhn/manager/download/ubuntu_20.04-update_group_1-ubuntu-2004-amd64-main-updates/getPackage/mysql-client-core-8.0_8.0.30-0ubuntu0.20.04.2.amd64-deb.deb  404  404 [IP: 172.17.21.30 443]

On SUSE Linux Enterprise Server clients:

Zypper command failure: Running scope as unit: run-raa43f3a5a76a4f46b13dfd0214e2586d.scope
        File './getPackage/NULL/d523df42e1b9f21c768aa196c41a08ec145441d2d830d9bc38d65fc02faabc42/supportutils-plugin-susemanager-client-4.3.2-150000.3.18.1.noarch.rpm' not found on medium 'https://suma.fqdn:443/rhn/manager/download/sles_15.3-update_group_1-sle-manager-tools15-updates-x86_64'

suma:~ # ll -d /var/spacewalk
drwxr-xr-x 6 wwwrun root 60 Aug 12 17:46 /var/spacewalk

suma:~ # ll -d /var/spacewalk/*
drwxr-xr-x 4 wwwrun root 27 Aug 31 10:20 /var/spacewalk/packages
drwxr-xr-x 4 wwwrun www  34 Aug 25 12:20 /var/spacewalk/rhn
drwxr-xr-x 3 root   root 21 Aug 12 17:46 /var/spacewalk/suse
drwxrwxr-x 2 wwwrun www   6 Aug 12 17:38 /var/spacewalk/systems

suma:~ # ll -d /var/spacewalk/packages/*
drwxr-xr-x 3547 wwwrun www 61440 Aug 31 10:38 /var/spacewalk/packages/1
drwxr-xr-x 4099 wwwrun www 69632 Aug 15 10:44 /var/spacewalk/packages/NULL

suma:~ # ll -d /var/spacewalk/packages/1/* | head
drwxr-xr-x    4 wwwrun www     59 Aug 31 10:36 /var/spacewalk/packages/1/000
drwxr-xr-x    3 wwwrun www     22 Aug 31 10:35 /var/spacewalk/packages/1/001
drwxr-xr-x    4 wwwrun www     55 Aug 31 10:37 /var/spacewalk/packages/1/002
drwxr-xr-x    3 wwwrun www     21 Aug 31 10:21 /var/spacewalk/packages/1/003
drwxr-xr-x    3 wwwrun www     36 Aug 31 10:38 /var/spacewalk/packages/1/004
drwxr-xr-x    6 wwwrun www    102 Aug 31 10:38 /var/spacewalk/packages/1/005
drwxr-xr-x    5 wwwrun www     84 Aug 31 10:38 /var/spacewalk/packages/1/006
drwxr-xr-x    4 wwwrun www     58 Aug 31 10:38 /var/spacewalk/packages/1/007
drwxr-xr-x    7 wwwrun www    109 Aug 31 10:37 /var/spacewalk/packages/1/009
drwxr-xr-x    7 wwwrun www    134 Aug 31 10:38 /var/spacewalk/packages/1/00a

The packages (e.g. wireless-regdb) are correctly stored in the database and assigned to the proper channel (for example wireless-regdb is available in both, updates and security channels which is correct). The metadata of the channels are also correct.  The problem is that for "tomcat" the package file does not exists due to incorrect permissions and ownership within "/var/spacewalk/packages/" directory. 

As a part of troubleshooting, it is needed to check if the "tomcat" user is allowed to access the package file, e.g.:

sudo -u tomcat ls /var/spacewalk/packages/1/e66/wireless-regdb/2022.06.06-0ubuntu1~18.04.1/all-deb/e666b45d8f34f0f5ebd1c3b0cfebea4d5f090950b35271e0b973c3badce01404/wireless-regdb-2022.06.06-0ubuntu1~18.04.1.all-deb.deb

All folders and the files in the sub-directory "/var/spacewalk" should be readable by the "tomcat" user. By default, the "tomcat" user is member of the "www" group, and the default owner of the "/var/spacewalk" directory is "wwwrun:www".

All files and folders that "tomcat" cannot access within the folder "/var/spacewalk" can be listed by running following command:

find /var/spacewalk/ -print0 | sudo -u tomcat perl -Mfiletest=access -l -0ne 'print unless -r'