---
title: "Notion API Custom emoji icons are validated: 2026-09-25 | Harbyn"
description: "Notion API Custom emoji icons are validated, announced Sep 25, 2026."
canonical: "https://harbyn.com/changes/notion/2026-09-25-custom-emoji-icons-are-validated"
last-updated: 2026-10-02
---

# Notion API Custom emoji icons are validated

Markdown version of <https://harbyn.com/changes/notion/2026-09-25-custom-emoji-icons-are-validated>.

Behavior change - Notion API. low severity. In effect.

A custom\_emoji icon on a page, database, data source, or callout must name a custom emoji in the integration’s workspace. Otherwise the request returns a validation\_error instead of saving an icon that reads back as null. Notion MCP applies the same check to page icons.

## Facts

| Fact | Value |
| --- | --- |
| Vendor | [Notion API](https://harbyn.com/vendors/notion.md) |
| Kind | Behavior change |
| Severity | low |
| Status | In effect |
| Announced | Sep 25, 2026 |
| Added to Harbyn | Oct 2, 2026 |
| Lead time | No dated deadline |
| Symbols | `custom_emoji`, `notion-create-pages`, `notion-update-page` |
| Review | Reviewed by a person, extracted by a model |

## Find it in your code

```sh
npx harbyn scan
```

This change names no identifier the scanner can match line by line, so the scan tells you whether your repository uses Notion API, from its packages and API hosts. Nothing leaves your machine.

## Sources

Where this event comes from: the page we read, when we read it, and the hash of that snapshot.

- <https://developers.notion.com/page/changelog.md> (changelog, fetched 2026-10-02 22:20 UTC, sha256 `ec279fb11111f1773751e95d79200a14dbac9e5c21565900e74f4509ca8de3e9`)

## Related changes

### More from Notion API

- [Timed-out page writes return HTTP 504](https://harbyn.com/changes/notion/2026-09-24-page-writes-return-504-when-a-request-times-out.md) (Behavior change, announced Sep 24, 2026)
- [Notion icon URLs are validated](https://harbyn.com/changes/notion/2026-09-23-notion-icon-urls-are-validated.md) (Behavior change, announced Sep 23, 2026)
- [Generic file MIME types are resolved from the filename extension](https://harbyn.com/changes/notion/2026-09-22-application-octet-stream-resolves-from-the-file-extension.md) (Behavior change, announced Sep 22, 2026)
- [Completing the query tool update in Notion MCP](https://harbyn.com/changes/notion/2026-09-29-completing-the-query-tool-update-in-notion-mcp.md) (Retirement, effective Sep 29, 2026)

### Changes at other vendors

- [Amazon Selling Partner API: ORDER\_CHANGE notifications add PreFulfillmentStatusChange for Amazon Autos](https://harbyn.com/changes/amazon-sp-api/2026-10-14-sp-api-updates-new-listings-items-api-ivp-values-in-eu5-jp-and-ca-stores-oct-3.md) (effective Oct 28, 2026)
- [BigCommerce: 301 redirects will apply only to storefront channels](https://harbyn.com/changes/bigcommerce/2026-10-07-301-redirects-now-apply-to-storefront-channels-only.md) (effective Nov 10, 2026)
- [GitHub: Secret scanning audit log business field changes to enterprise slug](https://harbyn.com/changes/github/2026-10-20-updates-to-github-secret-scanning-7.md) (effective Nov 12, 2026)
- [Jira / Atlassian Cloud: New IP address ranges in use from January 1, 2027](https://harbyn.com/changes/atlassian-jira/2026-10-16-atlassian-cloud-adds-new-ip-address-ranges.md) (effective Jan 1, 2027)

[All upcoming deadlines](https://harbyn.com/deadlines.md)