Google.GoogleApiException：Google.Apis.Requests.RequestErrorInvalid Value [400]错误消息[无效值]位置原因[无效]域[全局]

Question

使用此库(Google.Apis.Customsearch.v1, ver. 1.32.2.1146, in .Net VS2017 c# framework 4.7.1, from nuget)， 偶尔，我收到以下错误：

  

...服务 xxxxxx 引发了异常：   Google.GoogleApiException：       Google.Apis.Requests.RequestErrorInvalid Value [400]       错误[消息[无效值]位置[ - ]原因[无效]域[全局]]          在Google.Apis.Requests.ClientServiceRequest 1.d__34.MoveNext（）          ---从生成异常的先前位置结束堆栈跟踪---          在System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw（）中   Google.Apis.Requests.ClientServiceRequest 1.Execute（）in ...

在大多数情况下，一切都正常，代码没有任何变化。

使用的程序如下：

public DataTable RunSearch(string querySearch, string dateRestrict, string excludeTerms, string orTerms)
{
    string apiKey = ConfigurationManager.AppSettings["gsApiKey"];
    string searchEngineIdCX = ConfigurationManager.AppSettings["gsCX"];

    DataTable dtRes = getDt(); // create a custom table

    try
    {
        var customSearchService = new CustomsearchService(new BaseClientService.Initializer { ApiKey = apiKey });
        var listRequest = customSearchService.Cse.List(querySearch);
        listRequest.Cx = searchEngineIdCX;
        listRequest.Googlehost = "google.it";
        listRequest.DateRestrict = dateRestrict; // "d1"
        listRequest.ExcludeTerms = excludeTerms;
        listRequest.OrTerms = orTerms;
        IList<Result> paging = new List<Result>();
        int count = 0;

        while (paging != null && dtRes.Rows.Count < 100)  // max 100 free
        {
            listRequest.Start = count * 10 + 1; // every query gets 10 Results
            paging = listRequest.Execute().Items; // Each lap is a query that scales from 100 available
            if (paging != null)
            { 
                foreach (var item in paging)
                {
                    DataRow dr = dtRes.NewRow();
                    dr["Count"] = dtRes.Rows.Count + 1;
                    dr["Title"] = item.Title;
                    dr["Link"] = item.Link;
                    dr["Snippet"] = item.Snippet;
                    dtRes.Rows.Add(dr);
                }
                count++;
            }
        }
    }
    catch (Google.GoogleApiException gex)
    {
        string msgErr = "Error in " + this.GetType().ToString();
        logger.Fatal(msgErr, gex);
        throw;
    }
    catch (Exception ex)
    {
        string msgErr = "Error in " + this.GetType().ToString();
        logger.Fatal(msgErr, ex);
        throw;
    }

    return dtRes;
}

可能出现的错误是什么？ 提前谢谢。