When generating a keystore for MPP, please make sure that keystore password is the same as private key/alias password.
In mpp.json, in the following section the password (here encrypted) is listed in "passphrase":
In case the private key/alias password is different from keystore password, MPP would not be able to start and the following error (here tested with CSA 4.2 but the same or similar issue would be seen in other versions):
Error: pkcs12 cipherfinal error
would appear in hpmarketplaceportal.err.log.