> ## Documentation Index
> Fetch the complete documentation index at: https://developers.notion.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Releasing Notion-Version 2021-08-16
> about 4 years ago by Nishad Agrawal
We're releasing Notion-Version `2021-08-16` with the following *backwards incompatible* changes:
## Unknown Keys Will Fail Validation
Previously, our endpoints used to only validate against the expected keys in both request body parameters as well as query parameters resulting in some ambiguity between incorrect behavior and invalid inputs. Going forward, to improve the developer experience we will be raising validation errors if keys that are not supported by our API are passed in to requests.
**Migration Tip**
To safely migrate to `2021-08-16`, we recommend thoroughly testing your API calls against the `2021-08-16` version, to see if you get any validation errors due to this change. If you do, remove any parameters that are rejected due to unknown keys.
## Changes to Array Rollup Property Types
Starting with the Notion-Version header `2021-08-16`, we are introducing a change to the response for rollup properties on a page which are arrays. Number and date rollups are unaffected. Specifically, the `type` of elements within an array rollup has been made consistent with property types across other API endpoints:
| Before | After |
| :--------------- | :------------------ |
| `type: "file"` | `type: "files"` |
| `type: "text"` | `type: "rich_text"` |
| `type: "person"` | `type: "people"` |
An example rollup property value for an array of rich text values, using Notion-Version `2021-08-16`:
```json JSON expandable theme={null}
{
"properties": {
"sample text array rollup": {
"id": "NXTh",
"type": "rollup",
"rollup": {
"type": "array",
"array": [
{
"type": "rich_text",
"rich_text": [
{
"type": "text",
"text": {
"content": "hello world!",
"link": null
},
"annotations": {
"bold": false,
"italic": false,
"strikethrough": false,
"underline": false,
"code": false,
"color": "default"
},
"plain_text": "hello world!",
"href": null
}
]
},
{
"type": "rich_text",
"rich_text": [
{
"type": "text",
"text": {
"content": "foo bar",
"link": null
},
"annotations": {
"bold": false,
"italic": false,
"strikethrough": false,
"underline": false,
"code": false,
"color": "default"
},
"plain_text": "foo bar",
"href": null
}
]
}
]
}
},
}
}
```
## Append Block Children returns a list of blocks
The [Append Block Children](/reference/patch-block-children) endpoint will now return a list of the newly created [Block object](/reference/block) children.
Previously the endpoint returned the block object of the parent block. Developers can instead use the [Retrieve a block](/reference/retrieve-a-block) endpoint to get the full block object for a specified `block_id`.
This change allows developers to get `block_id`'s and additional information of the new blocks right after they're created. Note: only the first level block children are returned. To get sub-children, use the [Retrieve block children](/reference/get-block-children) endpoint.
```json JSON expandable theme={null}
{
"object": "list",
"results": [
{
"object": "block",
"id": "9bc30ad4-9373-46a5-84ab-0a7845ee52e6",
"created_time": "2021-03-16T16:31:00.000Z",
"last_edited_time": "2021-03-16T16:32:00.000Z",
"has_children": false,
"type": "heading_2",
"heading_2": {
"text": [
{
"type": "text",
"text": {
"content": "Lacinato kale",
"link": null
},
"annotations": {
"bold": false,
"italic": false,
"strikethrough": false,
"underline": false,
"code": false,
"color": "default"
},
"plain_text": "Lacinato kale",
"href": null
}
]
}
},
{
"object": "block",
"id": "7face6fd-3ef4-4b38-b1dc-c5044988eec0",
"created_time": "2021-03-16T16:34:00.000Z",
"last_edited_time": "2021-03-16T16:36:00.000Z",
"has_children": false,
"type": "paragraph",
"paragraph": {
"text": [
{
"type": "text",
"text": {
"content": "Lacinato kale",
"link": {
"url": "https://en.wikipedia.org/wiki/Lacinato_kale"
}
},
"annotations": {
"bold": false,
"italic": false,
"strikethrough": false,
"underline": false,
"code": false,
"color": "default"
},
"plain_text": "Lacinato kale",
"href": "https://en.wikipedia.org/wiki/Lacinato_kale"
},
{
"type": "text",
"text": {
"content": " is a variety of kale with a long tradition in Italian cuisine, especially that of Tuscany. It is also known as Tuscan kale, Italian kale, dinosaur kale, kale, flat back kale, palm tree kale, or black Tuscan palm.",
"link": null
},
"annotations": {
"bold": false,
"italic": false,
"strikethrough": false,
"underline": false,
"code": false,
"color": "default"
},
"plain_text": " is a variety of kale with a long tradition in Italian cuisine, especially that of Tuscany. It is also known as Tuscan kale, Italian kale, dinosaur kale, kale, flat back kale, palm tree kale, or black Tuscan palm.",
"href": null
}
]
}
}
],
"next_cursor": null,
"has_more": false
}
```
## Property IDs are now URL Safe
Endpoints that return property IDs as part of the response body will now return new URL safe encoded property IDs. Any request that uses property IDs (such as [Update a database](/reference/update-a-database) or [Update a page](/reference/patch-page)) should use the new URL safe ID.
This ensures all property IDs can be referenced in the URL of any new endpoints moving forward.
| Before | After |
| :------ | :------- |
| `DoS\` | `DoS%5C` |
| `title` | `title` |
| `vEKn` | `vEKn` |
## Empty database properties are now returned as `null`
Previously, empty properties of date, email, number, and rollup types were omitted from the page response. Now, these empty properties are returned with `null` values.
```json JSON expandable theme={null}
{
"object": "page",
"id": "a8b7e96d-22ce-44d8-991f-6c4535af6608",
"created_time": "2021-05-12T06:16:00.000Z",
"last_edited_time": "2021-08-12T21:36:00.000Z",
"cover": null,
"icon": null,
"parent": {
"type": "database_id",
"database_id": "70ff0393-6b40-4e76-afc4-4a26a9aa1606"
},
"archived": false,
"properties": {
"MyDate": {
"id": "GZT~",
"type": "date",
"date": null
},
"Description": {
"id": "RPld",
"type": "rich_text",
"rich_text": []
},
"Food group": {
"id": "W_iA",
"type": "select",
"select": null
},
"myRollup": {
"id": "%5Eu%3EC",
"type": "rollup",
"rollup": {
"type": "array",
"array": []
}
},
"MyRelation": {
"id": "_pL%3A",
"type": "relation",
"relation": []
},
"Price": {
"id": "dPVb",
"type": "number",
"number": null
},
"MyMultiSelect": {
"id": "%7B%40%5Co",
"type": "multi_select",
"multi_select": null
},
},
"url": "https://notion.so/a8b7e96d22ce44d8991f6c4535af6608"
}
```