WebForms UnobtrusiveValidationMode 需要“jquery”ScriptResourceMapping

在webconfig中找到

 <appSettings>
      <add key=" aspnet:UseTaskFriendlySynchronizationContext" value="true" />
      <add key="ValidationSettings:UnobtrusiveValidationMode" value="WebForms" />
</appSettings>

删除<add key="ValidationSettings:UnobtrusiveValidationMode" value="WebForms" />即可。

如果没有上面两句话，在webconfig中添加以下内容即可：

  <appSettings>
    <add key="ValidationSettings:UnobtrusiveValidationMode" value="None"/>
  </appSettings>

重新刷新界面，问题解决~