Error Updating 'Addon'

[naddral]

I keep gettibg the error message: 'Error Updating 'Addon': sun.security.validator.ValidatorException: PKIX path building failed..........

I can't read anymore but there seems to be a lot more info.
I know its a certificate issue, but where do I change it. There are no other error messages that come up apart from the one within minion.