diff --git a/IRaCIS.Core.Application/Service/SiteSurvey/TrialSiteSurveyService.cs b/IRaCIS.Core.Application/Service/SiteSurvey/TrialSiteSurveyService.cs
index 4173d3b17..2f4cdec0c 100644
--- a/IRaCIS.Core.Application/Service/SiteSurvey/TrialSiteSurveyService.cs
+++ b/IRaCIS.Core.Application/Service/SiteSurvey/TrialSiteSurveyService.cs
@@ -391,7 +391,7 @@ namespace IRaCIS.Core.Application.Contracts
             var result = await _trialSiteSurveyRepository.Where(t => t.Id == trialSiteSurveyId && t.TrialId == trialId).IgnoreQueryFilters()
                 .ProjectTo<LoginReturnDTO>(_mapper.ConfigurationProvider, new {  isEn_Us = _userInfo.IsEn_Us }).FirstOrDefaultAsync().IfNullThrowException();
 
-            var siteSurveryConfig = _trialSiteSurveyRepository.Where(t => t.Id == trialSiteSurveyId).Select(t => t.Trial.SiteSurveyConfigJsonStr).FirstOrDefault();
+            var siteSurveryConfig = _trialSiteSurveyRepository.Where(t => t.Id == trialSiteSurveyId).Select(t => t.Trial.SiteSurveyConfigJsonStr).FirstOrDefault()??string.Empty;
 
             result.SiteSurveyFiledConfig = JsonConvert.DeserializeObject<SiteSurveyFiledConfig>(siteSurveryConfig) ?? new SiteSurveyFiledConfig();
             return result;