I am trying to install a new Beta package of our app into a sandbox. The install fails and tells me that "Cannot upgrade to a managed-beta version" because " cannot be upgraded using a managed-beta version of this package because it is referenced by an extension package developed in this organization. Please install a managed-released version of this package to complete the upgrade."
But there is neither a package created from this sandbox nor an installed one that references the package i am trying to upgrade.
Any idea what else could cause the upgrade to fail?