Can you provide a little more context? What version of the modeler was used to create the mpk, and what error message did you receive?
Keep in mind that you may not be able to upgrade your mpk directly from an older version to the latest version. In this case you can try updating through an intermediary version.
In the mean time, here are a few docs that you may want to review:
Does the model includes the AppCloudServices module?
If so, that will probably be issue. Download the new version from the appstore and reconnect the login microflows.
This is related to the JAVA Api changes.