Resolution: When using X509Token in Authentication tab in an outbound security policy, and when the keystore specified in the X.509 Identity the field has alias, you need to give the alias name in the Certificate Alias field. If the alias specified in BW does not match the key alias in keystore, the above exception is thrown.
Solution: = = = = = Verify the alias names match. Use the Java keytool or openssl utility to view the key entries and find the key alias.