@julien-f Hi Julien,

I updated, recreated the backup job and now it works again. Thank you!

At least I think so. I worked with svn for years but that was ages ago and I never got into using git.

root@xo:/opt/xen-orchestra# git rev-parse master
de288a008d83b81ea93d7f45889972028ff9ed6c
root@xo:/opt/xen-orchestra# git branch
* master
root@xo:/opt/xen-orchestra# git fetch --dry-run
remote: Enumerating objects: 5, done.
remote: Counting objects: 100% (5/5), done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 5 (delta 3), reused 5 (delta 3), pack-reused 0
Unpacking objects: 100% (5/5), done.
From https://github.com/vatesfr/xen-orchestra
   e2515e531..52c4df4e4  ya_host_update_rev -> origin/ya_host_update_rev

@olivierlambert Hi Olivier,
I updated both instances, recreated the jobs and while backups on one instance now work again, on the other they still fail:

{
  "data": {
    "mode": "delta",
    "reportWhen": "failure"
  },
  "id": "1617829260018",
  "jobId": "72cb10c2-9949-4b9c-9618-33a2de5b0f79",
  "jobName": "customer-weekdays",
  "message": "backup",
  "scheduleId": "8333dbe9-6525-4f4f-a2da-cc6304254e96",
  "start": 1617829260018,
  "status": "failure",
  "infos": [
    {
      "data": {
        "vms": [
          "adbe367b-e33e-66f7-863c-e21ea8fa301a",
          "3837691a-c7c2-3ba9-143f-8afd0eb14f94",
          "cbee81b4-afb8-2773-a92a-dd4b3f83651f",
          "16dd84d4-2455-c293-2529-6311a98ecd46",
          "03037a27-bc51-7cfc-ad64-4146992fc95a",
          "324aa303-4404-20c1-c8f7-686ace47fd3f",
          "5544f33e-5fd9-12e1-ee65-f5849bd7f442",
          "d649555a-c134-fe17-aa68-d49b5ba50edf"
        ]
      },
      "message": "vms"
    }
  ],
  "tasks": [
    {
      "data": {
        "type": "VM",
        "id": "adbe367b-e33e-66f7-863c-e21ea8fa301a"
      },
      "id": "1617829261498:0",
      "message": "backup VM",
      "start": 1617829261498,
      "status": "failure",
      "tasks": [
        {
          "id": "1617829282666",
          "message": "snapshot",
          "start": 1617829282666,
          "status": "success",
          "end": 1617829289768,
          "result": "4815149b-0fb3-8cf3-8ec0-e32d5f3432fc"
        },
        {
          "id": "1617829289768:0",
          "message": "merge",
          "start": 1617829289768,
          "status": "failure",
          "end": 1617829289771,
          "result": {
            "message": "Cannot read property 'length' of undefined",
            "name": "TypeError",
            "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
          }
        }
      ],
      "end": 1617829291965,
      "result": {
        "message": "Cannot read property 'length' of undefined",
        "name": "TypeError",
        "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
      }
    },
    {
      "data": {
        "type": "VM",
        "id": "3837691a-c7c2-3ba9-143f-8afd0eb14f94"
      },
      "id": "1617829291966",
      "message": "backup VM",
      "start": 1617829291966,
      "status": "failure",
      "tasks": [
        {
          "id": "1617829292001",
          "message": "snapshot",
          "start": 1617829292001,
          "status": "success",
          "end": 1617829299739,
          "result": "e095c928-92c3-c085-1ea0-70584e5300e1"
        },
        {
          "id": "1617829299739:0",
          "message": "merge",
          "start": 1617829299739,
          "status": "failure",
          "end": 1617829299739,
          "result": {
            "message": "Cannot read property 'length' of undefined",
            "name": "TypeError",
            "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
          }
        }
      ],
      "end": 1617829301116,
      "result": {
        "message": "Cannot read property 'length' of undefined",
        "name": "TypeError",
        "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
      }
    },
    {
      "data": {
        "type": "VM",
        "id": "cbee81b4-afb8-2773-a92a-dd4b3f83651f"
      },
      "id": "1617829301116:0",
      "message": "backup VM",
      "start": 1617829301116,
      "status": "failure",
      "tasks": [
        {
          "id": "1617829301149",
          "message": "snapshot",
          "start": 1617829301149,
          "status": "success",
          "end": 1617829309295,
          "result": "b34ab48b-4077-0ad8-ea82-8c7233c82db6"
        },
        {
          "id": "1617829309296",
          "message": "merge",
          "start": 1617829309296,
          "status": "failure",
          "end": 1617829309296,
          "result": {
            "message": "Cannot read property 'length' of undefined",
            "name": "TypeError",
            "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
          }
        }
      ],
      "end": 1617829320279,
      "result": {
        "message": "Cannot read property 'length' of undefined",
        "name": "TypeError",
        "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
      }
    },
    {
      "data": {
        "type": "VM",
        "id": "16dd84d4-2455-c293-2529-6311a98ecd46"
      },
      "id": "1617829320279:0",
      "message": "backup VM",
      "start": 1617829320279,
      "status": "failure",
      "tasks": [
        {
          "id": "1617829320312",
          "message": "snapshot",
          "start": 1617829320312,
          "status": "success",
          "end": 1617829333295,
          "result": "1596e20b-e061-df4c-46d3-b2d5cce00094"
        },
        {
          "id": "1617829333295:0",
          "message": "merge",
          "start": 1617829333295,
          "status": "failure",
          "end": 1617829333295,
          "result": {
            "message": "Cannot read property 'length' of undefined",
            "name": "TypeError",
            "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
          }
        }
      ],
      "end": 1617829339414,
      "result": {
        "message": "Cannot read property 'length' of undefined",
        "name": "TypeError",
        "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
      }
    },
    {
      "data": {
        "type": "VM",
        "id": "03037a27-bc51-7cfc-ad64-4146992fc95a"
      },
      "id": "1617829339415",
      "message": "backup VM",
      "start": 1617829339415,
      "status": "failure",
      "tasks": [
        {
          "id": "1617829339440",
          "message": "snapshot",
          "start": 1617829339440,
          "status": "success",
          "end": 1617829343670,
          "result": "65a5a558-c30a-d0d8-5d02-57056bf6f7fc"
        },
        {
          "id": "1617829343671",
          "message": "merge",
          "start": 1617829343671,
          "status": "failure",
          "end": 1617829343671,
          "result": {
            "message": "Cannot read property 'length' of undefined",
            "name": "TypeError",
            "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
          }
        }
      ],
      "end": 1617829344953,
      "result": {
        "message": "Cannot read property 'length' of undefined",
        "name": "TypeError",
        "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
      }
    },
    {
      "data": {
        "type": "VM",
        "id": "324aa303-4404-20c1-c8f7-686ace47fd3f"
      },
      "id": "1617829344954",
      "message": "backup VM",
      "start": 1617829344954,
      "status": "failure",
      "tasks": [
        {
          "id": "1617829344986",
          "message": "snapshot",
          "start": 1617829344986,
          "status": "success",
          "end": 1617829352405,
          "result": "a0e9ca62-3e76-b6d1-cb0c-a3f0e602aded"
        },
        {
          "id": "1617829352405:0",
          "message": "merge",
          "start": 1617829352405,
          "status": "failure",
          "end": 1617829352405,
          "result": {
            "message": "Cannot read property 'length' of undefined",
            "name": "TypeError",
            "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
          }
        }
      ],
      "end": 1617829354244,
      "result": {
        "message": "Cannot read property 'length' of undefined",
        "name": "TypeError",
        "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
      }
    },
    {
      "data": {
        "type": "VM",
        "id": "5544f33e-5fd9-12e1-ee65-f5849bd7f442"
      },
      "id": "1617829354244:0",
      "message": "backup VM",
      "start": 1617829354244,
      "status": "failure",
      "tasks": [
        {
          "id": "1617829354276",
          "message": "snapshot",
          "start": 1617829354276,
          "status": "success",
          "end": 1617829358692,
          "result": "6f1be8c4-4559-35da-e0b7-efc042d9b174"
        },
        {
          "id": "1617829358692:0",
          "message": "merge",
          "start": 1617829358692,
          "status": "failure",
          "end": 1617829358692,
          "result": {
            "message": "Cannot read property 'length' of undefined",
            "name": "TypeError",
            "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
          }
        }
      ],
      "end": 1617829359980,
      "result": {
        "message": "Cannot read property 'length' of undefined",
        "name": "TypeError",
        "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
      }
    },
    {
      "data": {
        "type": "VM",
        "id": "d649555a-c134-fe17-aa68-d49b5ba50edf"
      },
      "id": "1617829359980:0",
      "message": "backup VM",
      "start": 1617829359980,
      "status": "failure",
      "tasks": [
        {
          "id": "1617829360005",
          "message": "snapshot",
          "start": 1617829360005,
          "status": "success",
          "end": 1617829365133,
          "result": "7b152071-5515-80c0-13fc-e390a13592d4"
        },
        {
          "id": "1617829365133:0",
          "message": "merge",
          "start": 1617829365133,
          "status": "failure",
          "end": 1617829365133,
          "result": {
            "message": "Cannot read property 'length' of undefined",
            "name": "TypeError",
            "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
          }
        }
      ],
      "end": 1617829367170,
      "result": {
        "message": "Cannot read property 'length' of undefined",
        "name": "TypeError",
        "stack": "TypeError: Cannot read property 'length' of undefined\n    at /opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:114:31\n    at Zone.run (/opt/xen-orchestra/node_modules/node-zone/index.js:80:23)\n    at /opt/xen-orchestra/node_modules/node-zone/index.js:89:19\n    at Function.fromFunction (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:20:27)\n    at SyncThenable.fulfilledThen [as then] (/opt/xen-orchestra/@xen-orchestra/backups/_syncThenable.js:2:50)\n    at TaskLogger.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:77:10)\n    at Object.run (/opt/xen-orchestra/@xen-orchestra/backups/Task.js:157:17)\n    at DeltaBackupWriter._deleteOldEntries (/opt/xen-orchestra/@xen-orchestra/backups/_DeltaBackupWriter.js:108:17)\n    at Array.<anonymous> (/opt/xen-orchestra/@xen-orchestra/backups/_VmBackup.js:150:70)\n    at Function.from (<anonymous>)"
      }
    }
  ],
  "end": 1617829367170
}

I can confirm having the same issue on two XO instances since upgrading to 5.78.2 / 5.80.0

P.S.:

I gave my latest "trick" another run:
Did a full copy of the VM within xo to the other host. While that job ran, I started the delta backup that finished OK. After the copy was done I deleted the copy and saw - as last time - that the host was coalescing. After finishing the sr's advanced tab is empty again and stayed empty.

@olivierlambert

• job 1 - type: delta - all VMs except xo - Mo-Fr 11:01 pm - concurrency: 1 - target: NFS repo on NAS1
• job 2 - type: full zstd - all VMs except xo - Sun 00:01 am - concurrency 1 - target: NFS repo on NAS2
• job 3 - type: full zstd - xo only - xo VM only - daily 10:00 pm - concurrency 1 - target: NFS repo on NAS1
• job 4 - type: pool metadata - daily 10:01 pm - target: NFS repo on NAS1

After the weekend the vm's problem reappeared.
So I'm almost certain it has something to do with the backup jobs, because the problem appears now fr the third time in a row after a weekend where everything was okay.

Mo-Fr a delta backup job is running at 11pm, on Sun 00:01am a full backup job is running. Both jobs backup all of the pool's vms, except xo and metadata which are fully backuped daily.

The last delta on Friday and the last full backup on Sunday finished i.O.

@olivierlambert said in Delta backup fails for specific vm with VDI chain error:

@mbt so what changed since the situation in your initial problem?

Nothing. No system reboot, no patch installations, no hardware reconfiguration, no XCP-ng server reconfoguration, ..

I just

• triggered the vm full copy in xo to the other host
• while the data was transferrred coalescing of the vm picked up until there were no outstanding jobs
• while the full backup was still running I started a backup-ng full backup job for the vm which worked
• I also manually started the delta backup job which also worked
• afterwards there was a short period of time where there were outstanding coalesce jobs for the dvi (depth 2) and I thought "here we go again.."
• but the system got it done and now everything seems to be okay for the moment.

I wish I had an explanation.

After the backups were done, I saw the usual problem, but this time the system was able to correctly coalesce it seems. The nightly delta backup finished okay and until now the problem hasn't reappeared.

I did a vm copy today (to have at least some sort of current backup) and while it was copying I was able to also run the delta backup job. Afterwards I found a vdi coalesce chain of 1 and when I checked after a while there were no coalesce jobs queued.
At this moment the weekly full backup job is running, so I expect to have some "regular" backups of the vm today and will monitor what happens on the coalescing side. I'm not getting my hopes too high, though