Error: RangeError: No value supplied for attribute start when editor.tryParseMarkdownToBlocks() parses Markdown containing ordered lists

[TimPchelintsev]

Thanks for great lib. I encountered this bug in both 0.41.1 and 0.42.0 and resolved it with Codex via workaround,
but it seems this should be fixed in the lib itself. I asked Codex to write bug report, reproduction, workaround and fix suggestion. Hope this helps!

Issue Summary

Error: RangeError: No value supplied for attribute start when editor.tryParseMarkdownToBlocks() parses Markdown containing ordered lists. The exception bubbles out of packages/core/src/schema/blocks/internal.ts (propsToAttributes → ProseMirror NodeType.computeAttrs).

Root Cause: packages/core/src/blocks/ListItem/NumberedListItem/block.ts defines start with default: undefined. When Markdown produces

1. …

without an explicit start (normal Markdown output), ProseMirror treats start as required and crashes.

Minimal Repro Markdown:

## Heading

1. First item
2. Second item

Feeding this into editor.tryParseMarkdownToBlocks reproduces the RangeError reliably.

Suggested Upstream Fix: Make start optional before it reaches ProseMirror—either give it a concrete default (default: 1) in NumberedListItem/block.ts, or map optional props to nullable PM attributes inside propsToAttributes.

Workaround (copy/paste ready): When building your schema, override only the numbered-list spec so start defaults to 1. Drop this into your editor setup:

import { BlockNoteSchema, createCodeBlockSpec } from '@blocknote/core'
import { defaultBlockSpecs } from '@blocknote/core/blocks'
// ...

const createSchema = () => {
  const blockSpecs = {
    ...defaultBlockSpecs,
    numberedListItem: {
      ...defaultBlockSpecs.numberedListItem,
      config: {
        ...defaultBlockSpecs.numberedListItem.config,
        propSchema: {
          ...defaultBlockSpecs.numberedListItem.config.propSchema,
          start: {
            ...defaultBlockSpecs.numberedListItem.config.propSchema.start,
            default: 1 as const,
          },
        },
      },
    },
    codeBlock: createCodeBlockSpec({ /* your existing options */ }),
  }

  return BlockNoteSchema.create({ blockSpecs })
}

const editor = useCreateBlockNote({ schema: createSchema(), /* ... */ })

That single override keeps BlockNote behavior identical while preventing the ProseMirror crash until the official fix lands.

[sportnak]

Worth noting - this fix doesn't work when you're using the @blocknote/server-util package. It fails the in the initialization of the schema with the error: No node type or group 'blockContent' found

[nperez0111]

This is also part of this issue: #2170 (comment)