This issue should track reoccurring pipeline errors which are observed from time to time.
Fixed issues should be checked:

• Error: System "micro02" failed to join the cluster: Failed to update cluster status of services: Put "https://10.69.231.229:9443/1.0/services": EOF
  Fixed in Test: Hold all snaps to prevent unplanned refresh #652
• lxc exec micro01 -- lxc launch ubuntu-minimal-daily:22.04 c1 -c limits.memory=512MiB -d root,size=2GiB -s remote -n default Launching c1 Error: Failed instance creation: Fetch project database object: Failed to fetch from "projects" table: Failed to fetch from "projects" table: Failed to fetch from "projects" table: sql: transaction has already been committed or rolled back
  Maybe related (due to resources): https://www.google.de/url?sa=t&source=web&rct=j&opi=89978449&url=https://discuss.linuxcontainers.org/t/database-error-sql-transaction-has-already-been-committed-or-rolled-back/14464/4&ved=2ahUKEwjd5Z6xy_CLAxUogP0HHVx1ChMQFnoECBUQAQ&usg=AOvVaw001EheGLCq7CzTSkLx6j-f
  • https://github.com/canonical/microcloud/actions/runs/13437321556/job/37542878760
  • https://github.com/canonical/microcloud/actions/runs/13653613796/job/38167679646
  • https://github.com/canonical/microcloud/actions/runs/14333304587/job/40174251902
  • https://github.com/canonical/microcloud/actions/runs/14930531723/job/42055476170
  • https://github.com/canonical/microcloud/actions/runs/14930554727/job/41945583317?pr=774
  • https://github.com/canonical/microcloud/actions/runs/16221024008/job/45801534172?pr=865#step:3:6316
  • https://github.com/canonical/microcloud/actions/runs/17234618780/job/48897915655?pr=887
  • https://github.com/canonical/microcloud/actions/runs/17521340182/job/49765605620
    Fixed in Service: Wait for LXD members to be ready after join #1246
• github.com/canonical/microcloud/microcloud/cmd/tui.(*InputHandler).getAllRows(0xc00031a550) panics panic: runtime error: index out of range [4] with length 4
  https://github.com/canonical/microcloud/actions/runs/13499838854/job/37715339968?pr=656
  https://github.com/canonical/microcloud/actions/runs/13786409444/job/38555414351
  https://github.com/canonical/microcloud/actions/runs/14310219002/job/40103165145?pr=733
  https://github.com/canonical/microcloud/actions/runs/14598026893/job/40948866855
  https://github.com/canonical/microcloud/actions/runs/14972399336/job/42056209191?pr=782
  Fixed in cmd/tui/handler: avoid panic at runtime due to trying to copy into an inner nil slice #799
• Error: System "micro02" failed to join the cluster: Failed to update cluster status of services: Failed to join "LXD" cluster: Failed to configure cluster: Failed to initialize member: Failed to initialize storage pools and networks: Failed to create storage pool "remote": Failed to run: rbd --id admin --cluster ceph --pool lxd_remote info lxd_lxd_remote: signal: killed
  https://github.com/canonical/microcloud/actions/runs/13519224737/job/37774700405?pr=666
  https://github.com/canonical/microcloud/actions/runs/16264171520/job/45916182877?pr=865
• Error: Failed to check if "lxd_cephfs" CephFS exists: Failed to run: ceph --name client.admin --cluster ceph fs get lxd_cephfs: exit status 1 (Error initializing cluster client: InvalidArgumentError('RADOS invalid argument (error calling conf_read_file)'))
  https://github.com/canonical/microcloud/actions/runs/13792565713/job/38576260053
• Error: System "micro02" failed to join the cluster: Failed to update cluster status of services: Failed to join "MicroCeph" cluster: failed to add service mgr: Failed to run: ceph auth get-or-create mgr.micro02 mon allow profile mgr osd allow * mds allow * -o /var/snap/microceph/common/data/mgr/ceph-micro02/keyring: exit status 1 (Error initializing cluster client: InvalidArgumentError('RADOS invalid argument (error calling conf_read_file)'))
  https://github.com/canonical/microcloud/actions/runs/13853126505/job/38764167452?pr=697
• Error: Failed start validation for device "eth1": MAC address "00:16:3e:29:5e:ee" already defined on another NIC
  https://github.com/canonical/microcloud/actions/runs/14454972118/job/40536205229?pr=750#step:3:6612
• ⨯ Error: Failed to request disk addition: Post "http://control.socket/1.0/services/microceph/1.0/disks?target=micro01": context deadline exceeded
  https://github.com/canonical/microcloud/actions/runs/16267366020/job/45926275850
  https://github.com/canonical/microcloud/actions/runs/16517071789/job/46710255729?pr=893#step:3:7936
  Fixed in Service: Increase the context deadline for adding MicroCeph disks #894
• Error: Failed restoring network: Failed adding OVS chassis "micro01" with priority 1138 to chassis group "lxd-net2": Failed to run: ovn-nbctl --timeout=10 --db ssl:10.233.39.247:6641,ssl:10.233.39.196:6641,ssl:10.233.39.87:6641 -c /proc/self/fd/3 -p /proc/self/fd/4 -C /proc/self/fd/5 --wait=sb ha-chassis-group-add-chassis lxd-net2 micro01 1138: signal: alarm clock (2025-07-25T09:13:24Z|00003|fatal_signal|WARN|terminating with signal 14 (Alarm clock))
  https://github.com/canonical/microcloud/actions/runs/16517982655/job/46713166163?pr=894
  -> Issue is already identified https://chat.canonical.com/canonical/pl/hy76o6k8dt8n9nk89rakzd1ysw
• When running e2e and deploying using Terraform, somehow the LXD cluster started to misbehave which caused Failed to begin transaction: failed to create dqlite connection: no available dqlite leader server found
  https://github.com/canonical/microcloud/actions/runs/17099508932/job/48492273368?pr=927
• ⨯ Error: System "micro02" failed to join the cluster: Failed to update cluster status of services: Failed to join "MicroCeph" cluster: failed to add service mon: failed to retrieve mon keyring: Failed to run: ceph auth get mon. -o /tmp/3755778528/mon.keyring: exit status 1 (unable to get monitor info from DNS SRV with service name: ceph-mon
  https://github.com/canonical/microcloud/actions/runs/17466017898/job/49602152088?pr=954#step:3:27015
• internal error, please report: running "lxd.lxc" failed: cannot create transient scope: DBus error "org.freedesktop.systemd1.TransactionIsDestructive": [Transaction for snap.lxd.lxc-14eb3434-fa1d-4ecd-bbce-19067088da76.scope/start is destructive (poweroff.target has 'start' job queued, but 'stop' is included in transaction).]
  https://github.com/canonical/microcloud/actions/runs/18712031576/job/53362757438?pr=1039
• Using the new Canonical runners we sometimes see E: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/noble-updates/universe/binary-amd64/Packages.xz File has unexpected size (1500056 != 1500192). Mirror sync in progress? [IP: 185.125.190.81 80]
  https://github.com/canonical/microcloud/actions/runs/19627629308/job/56205410401
  Fixed in Test: Retry apt and snap downloads #1140