AEM 6.4 post upgrade issue on Packages
Post upgrade from AEM 6.2 with SP2 to AEM 6.4 few of the packages are in not installed. The older version is on installed state.
For the new package is showing the message as "A different version seems to be installed:"

When i am trying to install manually i am getting the error javax.jcr.nodetype.ConstraintViolationException: OakConstraint0074: Attempt to add, modify or remove the system maintained property 'rep:externalId' and the package is not able install.