While decrypting database that is encrypted, I face the error Decryption failed. Error during unzipping (inflate).
I have tested the application and it works just fine. You just have to get the decryption key in order to use it. On the developer's page, there is a link to the XDA Forums where they teach you how to do this.
Secondly, download the latest version and follow the instructions on the page in order to decrypt the files: http://andreas-mausch.github.io/whatsapp-viewer/