当您使用更新面板时，您无法像上面那样调用javascript。你必须使用

 ScriptManager.RegisterStartupScript 

只需更改你的

ClientScript.RegisterStartupScript（this.GetType（），，alert（'无法删除'），true）;

到

 ScriptManager.RegisterStartupScript（updatePanelId，updatePanelId.GetType（）
，（'无法删除'），javaScript，true）; 

hi i want tp display javascript alert message in .cs file here is my script ClientScript.RegisterStartupScript(this.GetType(), "", "alert(''Cannot Delete'')", true);
uplcityDetail.update()//update panel id

in .cs file but code is executeing alert is not displaying can any tell me please

When you use update panel then you can not call javascript like above. You have to use

ScriptManager.RegisterStartupScript

Just change your

ClientScript.RegisterStartupScript(this.GetType(), "", "alert('Cannot Delete')", true);

to

ScriptManager.RegisterStartupScript(updatePanelId,updatePanelId.GetType()
                                   ,"('Cannot Delete')", javaScript, true);