diff --git a/IRaCIS.Core.Application/Service/QC/QCOperationService.cs b/IRaCIS.Core.Application/Service/QC/QCOperationService.cs
index 216cbcca9..351bcf4e3 100644
--- a/IRaCIS.Core.Application/Service/QC/QCOperationService.cs
+++ b/IRaCIS.Core.Application/Service/QC/QCOperationService.cs
@@ -1102,10 +1102,12 @@ namespace IRaCIS.Core.Application.Image.QA
 
                 await _scpStudyRepository.BatchUpdateNoTrackingAsync(t => t.Id == id, u => new SCPStudy() { SubjectVisitId = null });
 
+                if (fisrtPath.IsNotNullOrEmpty())
+                {
+                    var prefix = fisrtPath.Substring(1, fisrtPath.LastIndexOf('/') - 1);
 
-                var prefix = fisrtPath.Substring(1, fisrtPath.LastIndexOf('/') - 1);
-
-                await _oSSService.DeleteFromPrefix(prefix, true);
+                    await _oSSService.DeleteFromPrefix(prefix, true);
+                }
 
             }