Kenneth: Hi lc343765828, Can you create a page by the code below and test on your site? Does it get the same issue? <%@ Page Language="C#" %><%@ Register TagPrefix="CE" Namespace="CuteEditor" Assembly="CuteEditor" %><html><head> <title>example</title></head><body> <form id="Form1" runat="server"> <CE:Editor ID="Editor1" runat="server"> </CE:Editor> </form></body></html> Can you delete folder "CuteSoft_Client" and re-deploy it again? Keep me posted, Regards, Ken OK~~ I have created. Address: http://jxjc.tjpu.edu.cn/TESTs.aspx