Currently if JSS cannot find a certificate in the NSS database it will throw an ObjectNotFoundException without any message. To help troubleshooting JSS should include the certificate nickname in the exception message.
edewata fixed in master: * https://hg.mozilla.org/projects/jss/rev/19a0e2146a92 * https://hg.mozilla.org/projects/jss/rev/837c79476110 * https://hg.mozilla.org/projects/jss/rev/ca2c2fcfaf20