I made some modifications to an app that was started by another developer. The changes have been all right and now I want to publish to Google Play. I followed the tutorial link I added the version later I mainly adopted the part that uses ADT - > Android Tools -> Export Signed Application Package - Cryo a new keystore - Subscribe - Alinho and beauty gero Apk.
But Google Play gives me a message saying that SHA1 certificates are different.
Do I have to generate the apk with the same keystore that was created by the initial developer? What if he lost the file what can I do?