Ran into an issue where I was not able to list the installed ZenPacks and Zenoss was having issues starting. I think it was due to a ZenPack having issues and not being installed properly.

Drop into the container

serviced service shell -i -s FixZenpack zope bash

Change user and cd to ZenPack directory

su zenoss
cd /opt/zenoss/ZenPacks

Once there, remove the offending ZenPack. Replace ZENPACK.egg with the ZenPack

rm -rf ./ZENPACK.egg

Example:

rm -rf ./ZenPacks.zenoss.MikroTik-1.1.1.egg

Exit out of the container.

exit
exit

You can also hit ctrl+d twice.
Commit the Container

 serviced service shell -i -s FixZen zope bash

Restart the Zenoss.Core Service

service service restart Zenoss.Core