What causes "sequence object not found" in hcengineering/platform?

Create the missing Sequence document attached to board.class.Card

sequence object not found

Error message

sequence object not found

What it means

Creating a board Card requires a Sequence document attached to board.class.Card to assign the card's number. When findOne on core.class.Sequence returns undefined, numbering is impossible and this error is thrown. It indicates missing seed data in the workspace.

Source

Thrown at plugins/board-resources/src/utils/CardUtils.ts:22

  type TxOperations as Client,
  type TxResult,
  type Ref,
  type Space,
  type AttachedData,
  type Status
} from '@hcengineering/core'
import { showPanel } from '@hcengineering/ui'
import board from '../plugin'

export async function createCard (
  client: Client,
  space: Ref<Space>,
  status: Ref<Status>,
  attribues: Partial<AttachedData<Card>> & { kind: Card['kind'] }
): Promise<Ref<Card>> {
  const sequence = await client.findOne(core.class.Sequence, { attachedTo: board.class.Card })
  if (sequence === undefined) {
    throw new Error('sequence object not found')
  }

  const incResult = await client.update(sequence, { $inc: { sequence: 1 } }, true)
  const number = (incResult as any).object.sequence

  const value: AttachedData<Card> = {
    title: '',
    status,
    startDate: null,
    dueDate: null,
    number,
    rank: '',
    assignee: null,
    identifier: `CARD-${number}`,
    description: '',
    ...attribues
  }

View on GitHub (pinned to 63e28dc964)

Solutions

Create the missing Sequence document attached to board.class.Card
Re-run workspace seed/initialization that registers sequences
Restore Sequence documents from backup

Example fix

// before: error thrown because sequence missing
// after: ensure sequence exists
let seq = await client.findOne(core.class.Sequence, { attachedTo: board.class.Card })
if (seq === undefined) {
  await client.createDoc(core.class.Sequence, core.space.Model, { attachedTo: board.class.Card, sequence: 0 })
}
await createCard(...)

Defensive patterns

Strategy: validation

Validate before calling

const seq = await client.findOne(core.class.Sequence, { attachedTo: board.class.Card })
if (seq === undefined) throw new Error('Board card sequence not seeded')

Type guard

const isSequence = (s: Sequence | undefined): s is Sequence => s !== undefined

Try / catch

try {
  await createCard(client, space, status, attrs)
} catch (err) {
  if ((err as Error).message === 'sequence object not found') {
    await seedCardSequence(client) // create missing Sequence, then retry
    return createCard(client, space, status, attrs)
  } else throw err
}

Prevention

Ensure board workspace bootstrap creates the Card sequence
Add an integration test asserting Sequence exists before card creation
Avoid manual deletion of Sequence documents in production data

When it happens

Trigger: Calling createCard in a workspace where the Sequence attached to board.class.Card was never created or was deleted.

Common situations: Newly provisioned workspace without board sequence bootstrap; data migration dropped Sequence docs; test environments built from partial fixtures; admin cleanup removed Sequence objects.

Related errors

AI-assisted analysis of hcengineering/platform@63e28dc964 (2026-08-29). Data as JSON: /api/errors/0ba918d30675226c. Report an issue: GitHub.