mattermost-community/focalboard · error

at least one block is required

Error message

at least one block is required

What it means

ErrNoBlocksInBoardsAndBlocks is a sentinel error in the BoardsAndBlocks model. BoardsAndBlocks.IsValid() requires at least one block, and this error reports that the payload's Blocks array is empty.

Source

Thrown at server/model/boards_and_blocks.go:15

package model

import (
	"encoding/json"
	"errors"
	"fmt"
	"io"

	"github.com/mattermost/focalboard/server/utils"

	"github.com/mattermost/mattermost/server/public/shared/mlog"
)

var ErrNoBoardsInBoardsAndBlocks = errors.New("at least one board is required")
var ErrNoBlocksInBoardsAndBlocks = errors.New("at least one block is required")
var ErrNoTeamInBoardsAndBlocks = errors.New("team ID cannot be empty")
var ErrBoardIDsAndPatchesMissmatchInBoardsAndBlocks = errors.New("board ids and patches need to match")
var ErrBlockIDsAndPatchesMissmatchInBoardsAndBlocks = errors.New("block ids and patches need to match")

type BlockDoesntBelongToAnyBoardErr struct {
	blockID string
}

func (e BlockDoesntBelongToAnyBoardErr) Error() string {
	return fmt.Sprintf("block %s doesn't belong to any board", e.blockID)
}

// BoardsAndBlocks is used to operate over boards and blocks at the
// same time
// swagger:model
type BoardsAndBlocks struct {
	// The boards
	// required: false

View on GitHub (pinned to a84bbb65e3)

Solutions

1. Include at least one block in the Blocks array of the payload
2. Validate len(blocksAndBlocks.Blocks) > 0 client-side before calling the API
3. Skip the call or surface a user-facing message when there is genuinely nothing to import

Example fix

// before
await client.importBoardsAndBlocks({boards: [board], blocks: []})
// after
if (payload.blocks.length > 0) {
  await client.importBoardsAndBlocks(payload)
}

if (!payload.blocks || payload.blocks.length === 0) {
  throw new Error('at least one block is required before import')
}

try {
  await client.importBoardsAndBlocks(payload)
} catch (err) {
  if (err.message?.includes('at least one block')) {
    alert('Nothing to import: payload has no blocks')
  } else throw err
}

When it happens

Trigger: POST /api/v2/boards-and-blocks (or BoardsAndBlocks.IsValid()) with an empty Blocks array.

Common situations: Import tooling uploading boards without their blocks; filtering block lists (e.g. by board membership) before submission and ending up with zero items.

Related errors

• at least one board is required
• block fields size limit exceeded
• team ID cannot be empty
• board ids and patches need to match
• block ids and patches need to match

AI-assisted analysis of mattermost-community/focalboard@a84bbb65e3 (2026-08-30). Data as JSON: /api/errors/cc74618b08d97637. Report an issue: GitHub.