Notion page markdown edit returns 400 validation_error on a very large page and retrying never works

Symptom

HTTP 400 validation_error when updating page content as markdownadditional_data.limit_kind is page_record_counttags appear when the page is retrieved as markdownSame request used to return 500 internal_server_error and keeps failing on retry

Cause

Since October 2, 2026, a page with about 20,000 records (mostly blocks) is not loaded in full. An edit that targets a block that was not loaded, or would remove content that was not loaded, is rejected. Earlier the same case returned a 500, so retry logic written for 500 now loops on a permanent failure.

Fix

Do not retry this 400. Retrieve the page as markdown and edit only content outside the tags, or split the page into smaller pages. Read additional_data.limit for the cap.

ApplyCopy

On 400 validation_error where additional_data.limit_kind == "page_record_count": stop retrying and limit edits to content outside <unknown> tags

Affected

Update a page's content as markdown and the notion-update-page MCP tool, from 2026-10-02

Sources

• https://developers.notion.com/page/changelog

Last verified 2026-10-17 · Confirmed by 0 builders