diff --git a/IRaCIS.Core.Application/Service/Allocation/VisitTaskService.cs b/IRaCIS.Core.Application/Service/Allocation/VisitTaskService.cs
index b39d3ead9..24933c6de 100644
--- a/IRaCIS.Core.Application/Service/Allocation/VisitTaskService.cs
+++ b/IRaCIS.Core.Application/Service/Allocation/VisitTaskService.cs
@@ -408,7 +408,7 @@ namespace IRaCIS.Core.Application.Service
         [UnitOfWork]
         public async Task<IResponseOutput> AssignSubjectTaskToDoctor(AssignSubjectTaskToDoctorCommand assignSubjectTaskToDoctorCommand)
         {
-            var visitTask=  await _visitTaskRepository.FirstAsync(t => t.Id == assignSubjectTaskToDoctorCommand.Id);
+            var visitTask=  await _visitTaskRepository.FirstOrDefaultAsync(t => t.Id == assignSubjectTaskToDoctorCommand.Id);
 
             if (assignSubjectTaskToDoctorCommand.TaskOptType == TaskOptType.Assign || assignSubjectTaskToDoctorCommand.TaskOptType == TaskOptType.ReAssign)
             {