1. There is no "product" attribute in package command. Please remove it.
2. Why do you still package mxp? MXP has some limitations and is no longer supported in Extension Manager CC. You should package ZXP instead.
3. Extension Manager CS6 can't sign extension during package. We have a new free product called Adobe Exchange Packager which can package and sign extensions. You can sign in http://www.adobeexchange.com/ and go to Resources page to download it. The current version in this page can't package extension based on existing mxi file. The latest version meets your requirement and will be available in a couple of days.
Hi Carl, thanks for your feedback.
While this is likely to change, I am packaging MXPs so that I do not have to deal with the overhead of a signing certificate.
I am not using EM CC, as I mentioned I am using EM CS6 which I have to use for Fw CS6.
Could you please help me address the issue described in the original post. I have removed the product attribute and get the same errors.
I tried to build a zxp. Same error.
Could you try to package a ZXP through Extension Manager CS6 UI interactively?