I use leap transactional-server patten.

Today, exec zypper ref for update repo.

but 'Update repository of openSUSE Backports' update failed on following error.

Building repository 'Update repository of openSUSE Backports' cache
.............................................[error]Error building the cache:
[repo-backports-update|http://download.opensuse.org/update/leap/15.3/backports/]
Failed to cache repo (137).
History:
 - 'repo2solv' '-o' '/var/cache/zypp/solv/repo-backports-update/solv' '-X'
'/var/cache/zypp/raw/repo-backports-update'
   Command was killed by signal 9 (Killed; Out of memory?).

Skipping repository 'Update repository of openSUSE Backports' because of the
above error.

I try to clean /var/cache/zypp folder (rm -rf).

but same result.