Problem description
This exception occurs when no signature information exists in the app.
Solution
This exception occurs when no signature information exists in the app. We recommend that you use Eclipse or Android Studio to recompile and package the project. Signatures are required to distinguish apps with the same class name or package name and ensure that the correct package is installed. If an APK file uses a key signature, the file signed with another key will not be installed or used to overwrite the old version. This can prevent your installed app from being overwritten or replaced by a malicious third-party app. A signature is also the identity of a developer. It is the digital certificate generated by the developer, or the self-signed certificate. For more information about the signature process, see References.
References
https://developer.android.com/studio/publish/app-signing.html (Official signature documentation)