Solution: The KeyStore password and The Key password should be the same.
Changing both passwords using keytool
Change KeyStore password
keytool -storepasswd -new %newpassword% -keystore %YourKeyStore%.jks
replace %newpassword% with your actual password, same with YourKeyStore
Change Alias key Password
keytool -keypasswd -alias %MyKeyAlias% -new %newpassword% -keystore KeyStore.jks
Note: supply old passwords for both keystore and alias when asked for them
(quoted from http://karim-ouda.blogspot.com/2010/07/errors-solutions-5.html)