Using the SharePoint REST service to update items, ran into this error:

Unable to update the sharepoint document – An error occurred while processing this request.System.Data.Services.Client.DataServiceClientException: <?

xml version=”1.0″ …

…..

at System.Data.Services.Client.DataServiceContext.SaveResult.<HandleBatchResponse>d_1e.MoveNext()

The target list was set to require checkout before items could be updated.  Once I set require checkout to No, the REST service was able to update items.