Did not find the required 'results' property on the object wrapping a feed

Hi

I'm trying to update a property using the example here:

https://docs.microsoft.com/en-us/sharepoint/dev/sp-add-ins/complete-basic-operations-using-sharepoint-client-library-code)

ClientContext ctx = new ClientContext(site_uri+id);
Web web = ctx.web;
web.title = “new title”;
web.Update();
ctx.ExecuteQuery();

However I'm getting the following error:

Did not find the required 'results' property on the object wrapping a feed.

Does this indicate something wrong with what I'm sending to the server, or something wrong on the sharepoint server?

Thanks