When you build your application using a private modified copy of the mfc windows forms interfaces dll mfcmifc80 . dll , it will fail to install in the gac unless you replace the microsoft key with your own vendor key 使用mfc windows窗体接口dll ( mfcmifc80 . dll )的私有(修改过的)副本生成应用程序时,除非用自己的供应商密钥替换microsoft密钥,否则在gac中安装会失败。