diff --git a/Pages/Students/Index.cshtml.cs b/Pages/Students/Index.cshtml.cs
index f07db45..4e6189d 100644
--- a/Pages/Students/Index.cshtml.cs
+++ b/Pages/Students/Index.cshtml.cs
@@ -109,6 +109,7 @@ namespace _2021_backend.Pages.Students
 
         public async Task<IActionResult> OnPostReselectAllAsync(int? pageId,string errInfo)
         {
+            if (pageId == null) pageId = 0;
             foreach (var s in Context.Students)
             {
                 if (s.Status != status.不通过) s.Status = status.需调整时间;