Page edits return 400 when a page is too large to load
By Steven Van ·
The change covers the markdown API and Notion MCP, with edits restricted to content outside unknown tags.
Developers editing large pages through Notion's markdown API or notion-update-page MCP tool now receive HTTP 400 validation_error instead of HTTP 500 internal_server_error when an edit touches content that could not be loaded.
When the error occurs
The change applies when a page is too large to load in full, at about 20,000 records, most of them blocks. An edit fails if it targets an unloaded block or would remove unloaded content. Retrying the same request produces the same failure.
Editing around unloaded content
When retrieving a page as markdown, unloaded content appears as unknown tags. Edits should target only content outside those tags. The error response identifies the limit through additional_data.limit_kind, set to page_record_count, and additional_data.limit, which holds the limit. The markdown update documentation is linked from the October 2 release note.