How to write hyperlink custom field in a SharePoint list

[zorgoz]

Describe the bug

Unable to write SPO Hyperlink custom field. Getting Invalid request error.

Expected behavior

Field to be updated.

How to reproduce

• Cereata a list in SPO
• Add a hyperlink custom field, name URL
• Add two rows, complete the URL field for one, and leave it empty for the other.
• Prepare a graphClient instance

var items = await graphClient
    .Sites["siteId"]
    .Lists["listId"]
    .Items
    .GetAsync(requestConfiguration =>
    {
        requestConfiguration.QueryParameters.Expand = new[] { "fields" };
        requestConfiguration.QueryParameters.Top = 100;
    });

foreach (var item in items.Value)
{
    var fields = item.Fields?.AdditionalData;

    if (fields == null) continue;
    
    if (fields.TryGetValue("URL", out var _url) && _url is UntypedObject uo) // testing read
    {
        foreach (var (name, node) in uo.GetValue())
        {
            var scalarAsString = await KiotaJsonSerializer.SerializeAsStringAsync(node);
            $"{name}: {scalarAsString}".Dump();
        }

        continue;
    }

    var table = new UntypedObject(new Dictionary<string, UntypedNode>
    {
        ["url"] = new UntypedString("whateverurl"),
        ["description"] = new UntypedString("whatevertext"),
    });

    var updateFields = new FieldValueSet
    {
        AdditionalData = new Dictionary<string, object>
        {
            ["URL"] = table,
        }
    };

    await graphClient
        .Sites[siteId]
        .Lists[listId]
        .Items[item.Id]
        .Fields
        .PatchAsync(updateFields);
}

• The completed cell can be read back
• The patch throws an exception

SDK Version

5.87.0

Latest version known to work for scenario above?

No response

Known Workarounds

No response

Debug output

No response

Configuration

Windows 10, x64, nothing specific

Other information

ref: https://stackoverflow.com/questions/79714772/how-to-write-hyperlink-custom-field-in-a-sharepoint-list-using-graphapi

Sample on read ("Server" is also a custom field, which I can write using the same method):