It helps to boot up on the old v5 commit and check from that side too if you have both copy before the commit update.

Yep I can confirm that snapshot doesn't always work. But using the older v5 that used to work before the update does get it showing up on the newer v5 commit if I go through whole snapshot, revert, etc. one of those case work.

i'll try to snap and revert to the snap and tell you if its Ok this way for me

slowing verifying if its going down the countdown... luckily most of them are related so it's not too bad.

• Revert the SNAPSHOT and it magically find the disk...
• Create a new SNAPSHOT and it magically find the disk... (esp. if you don't have a snapshot on some VMs like me)
• SNAPSHOT sometime works but still missing disk so boot it up and disk show up
• Some claim migrating the VM works... (migration fail for me as it can't find the disk lol...)

There should be better solutions as sometime I want to keep old snapshots. Still testing other methods... as my old XO still finds everything... even though its loaded with the same CONFIG FILES and same XCP-ng machine metadata.

No disk on XO v5

Disk show up on v6

Fixed it by REVERTING the SNAPSHOT....

Seem others was able to migrate the VM out and back in to fix it as well which seem ridiculously time consuming lol . I might try that for those that have no snapshot as its a lost cost...

invisible VDIs on some SRs
they are seen as snapshots and not presented in XO5 web UI but you can see them in XO6 or by API

This is the SMlog on one of the machine. I cannot rule out qcow2 but I definitely upgrade it from back in the early release of 8.3a and 8.3b. If I did use qcow2 I probably install and forgot about it... but its definitely affecting every VMs on the XO (commit b89c2)

SMlog.txt
SMlog2.txt

I have also notice that all the VMs on the XO (commit b89c2) run on debian 12 all have missing disks.

FROM:
Xen Orchestra, commit 0a28a (Pre Update on XO disk available still as long as I use the old GUI)

TO:
Xen Orchestra, commit b89c2 (Post Update on XO missing Disks)
Surprisingly the VM still loads and run without the disks but extremely confusing...

Snapshots on it fail for both XO commit version with the following error might be a related issue too which I just notice now:

vm.revert
{
  "snapshot": "d0734350-87a4-97f8-97dc-9d9ac5c24b5d"
}
{
  "code": "INVALID_VALUE",
  "params": [
    "snapshot_metadata:HVM__boot_policy",
    "null"
  ],
  "task": {
    "uuid": "058f49ac-82cc-a49b-eaaf-d20e4a319432",
    "name_label": "Async.VM.revert",
    "name_description": "",
    "allowed_operations": [],
    "current_operations": {},
    "created": "20260106T02:19:26Z",
    "finished": "20260106T02:19:26Z",
    "status": "failure",
    "resident_on": "OpaqueRef:ea86afa1-6562-0eac-79fc-75be4ce1cb2a",
    "progress": 1,
    "type": "<none/>",
    "result": "",
    "error_info": [
      "INVALID_VALUE",
      "snapshot_metadata:HVM__boot_policy",
      "null"
    ],
    "other_config": {},
    "subtask_of": "OpaqueRef:NULL",
    "subtasks": [],
    "backtrace": "(((process xapi)(filename ocaml/xapi/xapi_vm_snapshot.ml)(line 432))((process xapi)(filename ocaml/xapi/xapi_vm_snapshot.ml)(line 428))((process xapi)(filename ocaml/xapi/xapi_vm_snapshot.ml)(line 471))((process xapi)(filename ocaml/xapi/message_forwarding.ml)(line 2334))((process xapi)(filename ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml)(line 24))((process xapi)(filename ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml)(line 39))((process xapi)(filename ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml)(line 24))((process xapi)(filename ocaml/libs/xapi-stdext/lib/xapi-stdext-pervasives/pervasiveext.ml)(line 39))((process xapi)(filename ocaml/xapi/message_forwarding.ml)(line 2292))((process xapi)(filename ocaml/xapi/rbac.ml)(line 188))((process xapi)(filename ocaml/xapi/rbac.ml)(line 197))((process xapi)(filename ocaml/xapi/server_helpers.ml)(line 77)))"
  },
  "message": "INVALID_VALUE(snapshot_metadata:HVM__boot_policy, null)",
  "name": "XapiError",
  "stack": "XapiError: INVALID_VALUE(snapshot_metadata:HVM__boot_policy, null)
    at Function.wrap (file:///opt/xo/xo-builds/xen-orchestra-202512260040/packages/xen-api/_XapiError.mjs:16:12)
    at default (file:///opt/xo/xo-builds/xen-orchestra-202512260040/packages/xen-api/_getTaskResult.mjs:13:29)
    at Xapi._addRecordToCache (file:///opt/xo/xo-builds/xen-orchestra-202512260040/packages/xen-api/index.mjs:1078:24)
    at file:///opt/xo/xo-builds/xen-orchestra-202512260040/packages/xen-api/index.mjs:1112:14
    at Array.forEach (<anonymous>)
    at Xapi._processEvents (file:///opt/xo/xo-builds/xen-orchestra-202512260040/packages/xen-api/index.mjs:1102:12)
    at Xapi._watchEvents (file:///opt/xo/xo-builds/xen-orchestra-202512260040/packages/xen-api/index.mjs:1275:14)"
}