Same here.
After upgrading from 1.7.8.8 to 8.0.1, somehow the Distribution API Client module was disabled by default, and I didn't see any module updates. After enabled, I see the updates, but all module related operations give the above errors. Either installing, updating, enabling, disabling and uninstalling modules, one of the following appears:
Environment variable not found: "DISTRIBUTION_API_URL".
- or -
Installation of the Modul *whatever* failed: No Entry in Employee->email