Microsoft Graph returns 422 when using $expand=children on a file driveItem

Question

I call the API GET https://graph.microsoft.com/v1.0/drives/{drive-id}/items/{driveItem-id}?$expand=children where the driveItem-id belongs to a file.

Yesterday the request worked normally, but today it returns a 422 error as shown below.

{
    "error": {
        "code": "notSupported",
        "message": "Children cannot be listed from an item that is not a folder",
        "innerError": {
            "code": "unprocessableEntity",
            "innerError": {
                "code": "getChildrenOnNonFolder"
            },
            "date": "2026-03-17T08:46:29",
            "request-id": "83a946e0-784c-469e-8cc0-c881ba0cfb3c",
            "client-request-id": "83e7345c-0746-e5bd-e718-73c2be348f9c"
        }
    }
}

Answer 1

The 422 response and the message Children cannot be listed from an item that is not a folder are expected when using $expand=children on a driveItem that represents a file rather than a folder.

The OneDrive/Graph driveItem model only exposes a children relationship for items that have a non-null folder (or package) facet. Files do not have children, so attempting to expand or list children on a file now correctly returns an error instead of silently succeeding.

To fix the issue:

1. Ensure that $expand=children is used only when the target driveItem is a folder (or package):
   • First get the item metadata without expand:

          GET /drives/{drive-id}/items/{item-id}
     

   • Check that the response has a non-null folder facet before calling with $expand=children or before calling /children.
2. For folders, use one of the supported patterns:
   • Get folder metadata and children in one call using $expand=children:

          GET /drives/{drive-id}/items/{folder-item-id}?$expand=children
     

     (Only valid if the item is a folder.)
   • Or list children directly:

          GET /drives/{drive-id}/items/{folder-item-id}/children
     

3. For files, remove $expand=children entirely, because files cannot have children. Use a simple GET:

      GET /drives/{drive-id}/items/{file-item-id}
   

If this previously “worked” on a file driveItem, the behavior was likely permissive or inconsistent and has since been corrected to enforce the documented rule that only folder/package items can have children.

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References:

• List children of a driveItem
• Get a DriveItem resource
• List thumbnails for a DriveItem