In Android, when I tried to install an unsigned app, I got an INSTALL_PARSE_FAILED_NO_CERTIFICATES error.

I did a lot of research, but creating and installing a signed apk file was the easiest approach.

[Reference]

・eclipse上で署名されたandroidアプリ(.apk)を作成する

・apkファイルインストール時のエラー一覧 - [Androidアプリ/Android] ぺんたん info

That’s all from the Gemba.