调用K/3 Cloud Web API接口报错

财务总账凭证保存：调用K/3 Cloud Web API标准接口时报下面错误信息，麻烦大神们帮忙看一下。

[{"operation":"PBYD_sipg_List.MBIClick.tbButton"}]
发生时间：15:04:10
错误来源： Kingdee.BOS.ServiceFacade.KDServiceFx
错误信息：{ctx == null}
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调用堆栈：
在 Kingdee.BOS.ServiceFacade.KDServiceFx.ServiceExecutor.Execute(KDServiceContext context, ServiceType svcType, String[] paraValues, SerializerProxy serializeProxy, ServiceType beginMethod)
在 Kingdee.BOS.ServiceFacade.KDServiceFx.ExecuteServiceModule.OnProcess(KDServiceContext context)
在 Kingdee.BOS.ServiceFacade.KDServiceFx.ModulePipeline.ExcuteRequest(KDServiceContext context)
在 Kingdee.BOS.ServiceFacade.KDServiceFx.RequestExcuteRuntime.BeginRquest(RequestExtractor requestExtractor, WebContext webCtx)
在 Kingdee.BOS.ServiceFacade.KDServiceFx.RequestExcuteRuntime.StartRequest(RequestExtractor requestExtractor, WebContext context)
在 Kingdee.BOS.ServiceFacade.KDServiceFx.KDSVCHandler.ExecuteRequest(WebContext ctx, RequestExtractor requestExtractor)
在 Kingdee.BOS.ServiceFacade.KDServiceFx.KDSVCHandler.ProcessRequestInternal(WebContext webCtx, RequestExtractor requestExtractor)